Replace step 1 with sauteèing the onions and garlic in oil and dried basil. Sprinkle with flour and mix in tomato paste after onions have softened. Transfer all contents to slow cooker.
Replace half the chicken with chorizo or Italian sausage and brown it in a pan before adding to the slow cooker.
Add 1-2 grated or finely chopped carrots into the slow cooker at the start.
