Place the chicken breasts in your slow cooker. Top with the passata, tomato paste, beans, red capsicum, red onion, cherry tomatoes and mexican spice blend. Place the lid on and cook on high for 6 hours. You can check after 4–5 hours and add 1 cup of water or stock if the liquid has evaporated too much.
Preheat the oven to 200°C conventional (180°C fan-forced).
If your slow cooker bowl isn't ovenproof, transfer the contents of the slow cooker to a baking dish. Shred the chicken with forks, then stir through the corn and season well. Add the tortilla strips and use a large spoon to push them down under the sauce. Sprinkle over the grated cheese and bake for about 20 minutes, until the cheese has melted and everything is warmed through.
Optional serving suggestion: Serve with a fresh tomato salsa and some shredded lettuce. This will go over the budget, so totally your call.
You can buy Mexican spice blend in any good food grocer or produce store. Most big supermarkets now have it too, in sachets in the spice section (just look for ingredients such as paprika, cumin, oregano, onion and garlic).