Healthy Oat Slice With Rhubarb And Ginger (Gluten-free)
on May 26, 2014, Updated Mar 11, 2022
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If you’ve ever tried a fruit crumble or crisp, or enjoyed an oat flapjack or granola bar, you’ll love this 7-ingredient healthy oat slice with rhubarb and ginger. Perfect for late night sweet snack cravings, lunch boxes and more!
Growing up in England, many gardens had a rhubarb patch! Rhubarb is very sour when eaten raw, but cook it with a little sweetness and it’s perfect in cakes, crumbles and bars.
I loved the ‘rhubarb crumble and custard’ that we Brits know so well when I was a child. I also loved a sort of chewy, oaty slice that we call ‘flapjack’.
So I decided to see if I could come up with a healthy rhubarb recipe that was a kind of cross between a rhubarb and ginger crumble and a rhubarb flapjack. And I think I actually got it about right first time with this healthy rhubarb slice!
What you’ll love about them
- You only need 7 ingredients to make them.
- They take less than 15 minutes to make (plus 30 minutes to bake!).
- They’re mostly made from wholesome gluten free ingredients, so they’re a healthy treat.
- They’re delicious! Slightly crunchy on top, chewy and fruity in the middle. Like a cross between a rhubarb crumble and a flapjack.
About the ingredients
Rhubarb: You only need about 4 ‘stalks’ of rhubarb. Find out when it’s in season where you live and grab some while you can! Chop off any tough or leafy parts, then chop into small pieces.
Brown sugar: Just a little, to take the edge off the sourness of the rhubarb.
Butter, brown sugar and honey: To mix into the oats. You can use just honey if you prefer to make them without refined sugar. I do find the mixture holds together better if you add a little brown sugar, however. Feel free to replace the butter with coconut oil, too.
Gluten free rolled oats: Check that the oats you use actually are gluten free (if that’s important for you). Don’t use quick oats.
Almond flour: This acts like a flour and also helps the oat mixture to stay together.
Ground ginger: You can add a bit of chopped candied ginger, preserved ginger or stem ginger too, for an extra gingery taste. Go easy though at first. You can always add more next time!
How to make a healthy oat slice
These healthy oat slices with rhubarb and ginger are super easy to make.
First, cook the rhubarb for about ten minutes with a little brown sugar.
To make the oat mixture, melt a little butter and brown sugar and plenty of honey together before adding oats, ground almonds and ground ginger.
Finally, assemble everything by pressing two thirds of the oat mixture into the bottom of a baking tray. Then spread the cooked-down rhubarb on top.
Sprinkle the rest of the oat mixture on top of that. Then bake!
The finished result is so delicious and healthy.
As you take a bite there’s the crumbly, oaty top, then the beautiful rhubarb gets your taste buds singing as only rhubarb does. Finally, there’s the slightly chewy flapjack-y layer on the bottom.
How to eat this healthy oat slice
- with healthy ice cream or nice cream on top
- with custard or cream if you fancy a treat
- as a guilt-free lunch box, after school or late night treat
Variations
If you live in a place where you can’t easily find rhubarb, you could go ahead and try these with berries (just don’t cook them first) or really any other fruit.
You could also try nectarines or peaches, but don’t add sugar or cook the fruit down first.
Please let me know how they turn out if you do try that.
Enjoy!
More things to know (recipe FAQ)
Cooking the rhubarb for just a short time with a tiny bit of sugar makes it just the right consistency when the bars are baked. Undercooked rhubarb doesn’t taste great!
Nothing! These oat slices are definitely on the more crumbly side when they’re warm, almost like a crumble or crispy. Feel free to eat when still warm, but they’re better eaten with a bowl and spoon. Yum!
If you let them cool completely, or even chill them in the fridge, they’ll hold together better.
Yes, that will work fine! If you also replace the honey with maple syrup or another sweetener, the slices are then vegan.
For a stronger ginger taste, chop up one or two ‘balls’ of preserved ginger or pieces of stem ginger into small pieces. It’s best to start with less and then increase next time you make these!
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More healthy sweet snacks
- These homemade healthy granola bars with pecans and white chocolate are so easy to make!
- This peanut butter healthy mug cake is ready in just 2 minutes.
- Ever made your own granola? Try this low sugar homemade granola and you’ll never buy granola again!
Fan of healthy sweet snacks? Check out this 50+ healthy sweet snacks that don’t taste boring!
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Healthy Oat Slice With Rhubarb And Ginger (Gluten-free)
Equipment
Ingredients
For the rhubarb
- 4 full-size ‘stalks’ fresh rhubarb, chopped into 1-cm pieces
- 2 tablespoons brown sugar
For the oaty mixture
- 3 tablespoons butter
- 1/4 cup brown sugar
- 3 1/2 tablespoons clear honey
- 2 1/2 cups gluten-free rolled oats*
- 1 cup almond flour
- 1 teaspoon ground ginger
- custard, ice cream or cream, to serve (optional)
Instructions
- Pre-heat the oven to 410F/210C and line a 8 x 8 inch pan with baking paper.
- Heat the rhubarb and sugar in a large pan with 1 tablespoon water for 10 minutes until cooked down but with some pieces of rhubarb still whole. Set aside.
- In another pan, melt the butter, sugar and honey, then take off the heat and stir in the oats, ground almonds and ginger until all the oats are well coated.
- Spoon two thirds of the oaty mixture into the baking tray and press down well with the back of a metal spoon. Spread the rhubarb over the oats, then sprinkle the rest of the oaty mixture over the top.
- Bake for 20 to 25 minutes or until the oats are golden brown. Leave to cool before cutting into slices or serve while still slightly warm with custard, ice cream or cream. Will keep in an air-tight container in the fridge for a few days.
By “ground almonds” do you mean coarse ground or almond flour?
Hi Melissa! In the UK (where I was when I posted this recipe!) almond flour and ground almonds are interchangeable – so either is fine! Hope you enjoy the recipe!
Hi Helen,
Love your blog, which I have just discovered, and this recipe was exactly what I was looking for, It’s cooling right now.
RAIN IS LOVELY! There would be no lovely rhubarb without it! The smell of the earth, the cool air and it makes everything so green!
It took me ages to readjust after living in Morocco. Last year I went to Greece for the first time and now I will always long for that azure sea!
Love and Thanks,
Rosemary
Hello Rosemary. What a lovely message to wake up to today! I always appreciate feedback, so thank you so much for taking the time to comment.
This is an older recipe with not-so-perfect photos, but I’m so glad it turned out well. This is still one of my dad’s favourite recipes!
I’m so happy you’re enjoying the blog.
Wow, Morocco! I once visited Tetouan for just 1 day from Spain which was an incredible (if not a little nerve-wracking) experience. The food there must be amazing!
Hi this recipe sounds divine and I am about to go pick some rhubarb from my garden and make it right now!
I just wanted to point out however that this isnt a gluten free recipe as oats are what need to be avoided in a gluten free diet, especially with the coeliac disease.
Thanks 😊
Hi Ciara! So pleased you’re going to give this a go (it’s one of my dad’s favourites!). And thanks too for drawing the gluten free issue to my attention. It seems that oats should be gluten free but there can be a problem with contamination, which as you point out can be really disastrous for those with coeliac disease. I think I’ll add a note to my recipe! Thanks again! 🙂
I just made this, so yum! I cooked the rhubarb with some stem ginger and the syrup from the jar instead of sugar, which worked really well. I also replaced the butter with coconut oil which made a nice change. Thanks for the recipe!
Hello, Jess. So happy to hear that you tried this and enjoyed it, and even made some successful substitutions! I must make this again soon – it’s my dad’s favourite!
These look fab! I’ve been given a jar of preserved ginger and wondered if I could use that instead of ground ginger. If so, I wonder how much?
Hello, Maz! Ooh, now there’s a question! You can definitely use the preserved ginger instead of ground. Why not? It’s just for a hint of a gingery taste, after all, so if I were you I’d chop up finely and add one or two balls of the preserved ginger and see how you go with that. Let me know how you go!
Hi, I found the cooking temperature you suggested was too hot. My crumble-topping started to burn. (Using regular bake, not fan-forced). Have dialled it back to 180C and shifted it down a rack level. Is smelling wonderful right now so might have saved it!
Thanks for this GF recipe. What a treat. 👍
Hello Gilly – thanks so much for this feedback on the cooking temperature. Have reminded myself to give this one a go again in my new oven and see if I need to amend. I hope you enjoyed them! 🙂
Argh, I STILL live in a flat with no garden! It drives me mad as I’ve attempted growing bits and pieces in pots but nothing has thrived as yet. These bars look beautiful. Even better with fresh-picked rhubarb in the mix! I’d be interested to know if you think there are any peculiar behaviours amongst Australians? You are right though, stereotypes aside, different countries do seem to have quite distinct behavioural differences xx
It’s actually a tease living here with my parents and their garden for a month, Laura, because I know that I’ll soon be back to a flat with no garden! My one and only attempt at growing something myself was a pot of mini tomatoes on my balcony in Greece, but they turned out really small and tough. So glad you like the bars. Hmmm … Australians … I’ll think about that more when I’m there again this time, but one thing I did wonder is why they think it’s weird to wear slippers when it’s cold! 🙂
I love that you have been to same many countries Helen. I’m moved to different states within the US and too have found many differences. Most notably, when I lived in Eastern Florida everyone would ask my religion. They were obsessed with religion, particularly Baptist. That was hard to deal with because if you said anything other than Baptist they would want to talk your ear off about converting.
Anyhow, I love that you picked your own rhubarb for this treat. It looks delicious!
lol … that’s funny about the Florida baptists, Cindy! That must have got old pretty fast! I find it really fascinating that you have so many differences between states over there in the US. I’d love to do a big road trip one day to experience some of them for myself. So glad you like the rhubarb slices!
Helen, we have to join the rhubarb fan club too and your bars look amazing! Adore the combination of rhubarb and ginger. We feel the same way as you do about new and old places, and it is so interesting and rewarding to experience different cultures, languages and the best of all different cuisines! Hope you are having a wonderful week in beautiful England 🙂
Cheers,
J+C
Oh, please do join the rhubarb club, girls! I can imagine that there is a perfect wine to go with it! I really hope you are both having a beautiful week, too. 🙂
I’m visiting your site for the first time and you baked with one of my favorite ingredients! I love rhubarb, and have been baking a lot with it lately. I’ve only combined it with berries this far, and that needs to change — these look incredible! You’re so lucky you’ve gotten to love in so many different countries — I’ve been to Greece and England and would love to have stayed much longer!
I must have done that just for you, Marcie! I loved your post on the beautiful Mary Frances’ site (isn’t she sweet?) and am looking forward to hopping over to check out your site, too. Thanks so much for dropping by to say hi and so glad you like the rhubarb slices – I was really pleased with how they turned out.
Ah, comparisons are inevitable when moving around, especially for the weather, and especially from warmer to more frizzling 🙂 My husband comes from Provence and I hear it every day 🙂
Haha … yes, I have to be careful that I don’t moan too much about the weather now that I’m here in England. It’s very tempting but I’m trying to follow my own advice and be positive!