Preheat oven to 375.
Prepare cauliflower rice by cutting into florets, placing in your food processor and pulsing until it reassembles rice. You should have about 4 cups. (Alternatively you could also use store bought cauliflower rice)
Heat olive oil over medium heat in saute pan. Add garlic, chicken, broccoli, chicken broth, salt and pepper.
Bring to simmer, turn to low, cover and cook until chicken is cooked through and broccoli is tender, about 15 minutes.
Add cauliflower rice to chicken and broccoli. Stir and cook additional 5 minutes.
Combine 3 cheeses in a small bowl. Stir into cauliflower rice (reserving 1/2 cup for topping) along with the pesto.
Spread mixture into 13"x9" glass pan or other casserole pan. Top with remaining cheese.
Bake for 20-25 minutes until cheese is melted. Serve warm.