Place chicken and salsa in the bowl of your slow cooker. Cook on high for 4 hours or 6 hours on low. Before serving, shred the chicken between two forks.
Cook the cauliflower rice:
Stovetop: heat a large non-stick pan over medium-high heat, and add the oil to warm it up. Add the riced cauliflower and sauté for about 5 minutes until the cauliflower rice is heated through and tender.
Microwave: place the cauliflower rice in a microwave-safe bowl with ¼ cup water. Cover with plastic wrap to trap the heat in. Heat it for about 4 minutes, stopping to stir once or twice to ensure even heating. If you're using frozen riced cauliflower, you can steam it in a bag and follow the package directions.
Once the cauliflower rice is hot, add the cilantro, and stir to combine.
Meal Prep Assembly:
Line up 4 meal prep containers. Divide the cilantro cauliflower rice among the 4 containers. Top with shredded chicken, cheese, and black olives.
Pack the guacamole and sour cream in a separate lidded container. If eating these from home, top the bowls with these toppings after warming up.
Meal time:
Warm the chicken burrito bowls in the microwave for about 2 minutes, stopping halfway through to stir a little for even heating. Once hot, top with guacamole and sour cream if using.