Preheat oven to 400°F.

Spray a 9”x13” casserole dish with nonstick spray; set dish aside.

Fill a large pot with water and bring to a boil over high heat.

Quarter each of the heads of broccoli to create 8 large pieces of broccoli. Once pot is boiling, add broccoli and cook for 2 minutes. Remove broccoli and set aside to cool. Once cool, chop broccoli into bite-sized pieces.

Using the same pot of water, cook pasta according to package instructions. Once pasta is done cooking, drain and set aside.

Meanwhile, add olive oil to a large, deep skillet and place over medium-high heat. Once hot, add cubed chicken breasts. Saute, stirring occasionally, for 6-7 minutes, or until chicken is browned. Remove chicken and set aside. (Note: chicken will not be fully cooked at this stage.)

Using the same skillet, add butter, onions and garlic; stir until well combined. Sauté, stirring occasionally, for 3-4 minutes.

Add flour, Italian seasonings, salt and pepper; stir until well combined. Continue cooking, stirring often, for 1-2 more minutes.

Add milk and chicken stock; stir until well combined. Bring mixture to a boil over medium-high heat. Once boiling, add half-and-half along with the cubed chicken and broccoli (from above). Once mixture returns to a boil, remove skillet from heat and transfer mixture into the prepared casserole dish.

Add cooked pasta to dish and stir until well combined.

Top dish with Parmesan and mozzarella cheeses.

Bake for 15-20 minutes, or until top is golden brown.