• Preheat the oven to 350F/175C (fan oven). If using a conventional oven, increase to 350F/180C) . Lightly grease 2 x 8-inch (20cm) round cake pans with butter, or line with baking paper instead.
• Combine the flour, salt, baking powder and baking soda in a medium bowl, then set aside.
  2½ cups all-purpose flour, 1 teaspoon salt, 1½ teaspoons baking powder, ¾ teaspoon baking soda
• Beat the butter and sugar together in another medium bowl with an electric whisk until light and fluffy (2 to 3 minutes). Scrape down the sides with a silicon spatula regularly.
  1 cup unsalted butter, 1 cup light brown sugar
• Whisk in the eggs one at a time.
  2 large eggs
• Beat in the yogurt, bananas and peanut butter until smooth.
  ½ cup Greek yogurt, 1½ cups mashed ripe bananas, ⅓ cup peanut butter
• Stir in the flour little by little with a wooden spoon until totally mixed in. Finally, fold the chocolate chips through the batter.
  1 cup chocolate chips
• Divide the batter equally between the two pans and smooth down. Then bake for 35 to 40 minutes, or until the cakes are springy to the touch and a skewer or small sharp knife poked into the center comes out without raw batter on it. Let cool for a while, then turn out onto a wire rack to completely cool.

For the frosting

• Whisk together the peanut butter, butter and vanilla with an electric handheld whisk. Then whisk in the milk little by little.
  ½ cup peanut butter, 2 tablespoons butter, 1 teaspoon vanilla extract, 3 tablespoons milk
• Fold in about half the powdered sugar (icing sugar) and cocoa, then whisk until well combined. Whisk in the rest until the frosting is smooth and spreadable. If too dry, add a drizzle more milk, if too wet, add a little more powdered sugar.
  1½ cups powdered sugar, ¼ cup unsweetened cocoa powder
• When the cakes are completely cool, spread half of the frosting on the top of one, then place the other cake on top. Spread the rest of the frosting over the top of the cake, then decorate with peanuts (if using). Will keep in an airtight container for at least 4 days (possibly longer - never lasted that long!)
  salted or unsalted peanuts