In a large bowl mix together the chicken fillets, smoked paprika, sugar, mixed herbs, garlic, wine vinegar and 3 tablespoons of olive oil.
Season with salt and freshly ground pepper, Cover and marinate in the fridge for 2-4 hours.
Preheat the oven to 400°F First make the potato stack. Layer the par-boiled potato slices in a well-buttered 20cm spring-form cake tin, alternating with tablespoons of crème fraiche and a sprinkling of mozzarella.
Finish with a layer of mozzarella. Season the layers generously as you go with salt and freshly ground pepper.
Bake the potato stack for 30-40 minutes, until golden-brown. Meanwhile, toss the chopped onion with the remaining olive oil. Spread the onion in a roasting tray and roast in the oven on a shelf above the potato stack for 15 minutes, stirring now and then.
Add the marinated chicken breasts and roast for 25 minutes, until the chicken is cooked through.
Meanwhile, make the barbecue sauce. In a small, non-stick saucepan mix together the onion, garlic, sugar, vinegar, paprika and ketchup. Cook gently, stirring often, for 10 minutes until thickened and fragrant.
Make the coleslaw by mixing together the cabbage, carrot, apple, raisins and mayonnaise. Season with salt and freshly ground pepper.
Serve the chicken with the barbecue sauce, a dollop of coleslaw and a slice of the potato stack.