Heat up the olive oil gently in a heavy flat-bottomed pan (or a proper tagine), then layer up the onions, garlic, eggplant/aubergine, spices, prunes and herbs. Lay the chicken over the top, then grind over a little salt and pepper.
Squeeze over the lemon juice and pour over the stock. Put the lid on the pan and let the tagine simmer for about 45 minutes to an hour. Stir the ingredients about half way through cooking.
Shortly before the end of the cooking time, dry roast the almonds in a skillet/frying pan until lightly browned. Put aside.
Serve the tagine with hot couscous. Sprinkle over the reserved herbs plus some toasted flaked almonds.
Although I haven't tried it, I suspect that this recipe would work very well indeed using a slow cooker. Let me know if you give it a go!