Place a paella pan over medium-high heat. Add chorizo and cook, stirring to break up any chunks, until browned and crumbly, about 5 minutes. Add chicken; cook and stir until no longer pink in the center and the juices run clear. Transfer chicken and sausage to a plate, leaving drippings in the pan.

Reduce the heat to medium and add 2 cups of cauliflower rice. Cook and stir until cauliflower is browned slightly, about 5 minutes. Add onion, bell pepper, salt, pepper, and garlic; cook until fragrant, about 2 minutes.

Pour canned tomatoes into the pan. Add bay leaves, thyme, saffron, and basil; mix well. Return sausage and chicken back to the pan. Stir in water, tomato paste, and bouillon until well combined. Bring to a boil, then reduce heat to medium-low, cover, and simmer for 15 minutes.

Remove the lid and fold in peas and remaining 1 cup cauliflower rice. Place frozen tilapia fillets on top of paella mixture; cover and steam for another 10 minutes. Remove the lid and check for doneness. Break apart fillets with a wooden spoon and stir to incorporate chunks of fish into paella.