Preheat the slow cooker if necessary; see the manufacturer's instructions. Heat the oil in a frying pan, add the mince and onion and fry, stirring, for 5 minutes, breaking up the mince with a spoon until it is browned.
Stir in the garlic, paprika, chillies and cumin and cook for 2 minutes. Stir in the flour. Mix in the tomatoes, kidney beans, stock and sugar, season with salt and pepper and pour the mixture into the slow cooker pot. Cover with the lid and cook on low for 8–10 hours.
Stir the chilli, then arrange the tortilla chips on top. Sprinkle over the remaining ingredients, lift the pot out of the housing using oven gloves and brown under a hot grill until the cheese just melts. Spoon into bowls to serve.