Preheat oven to 350 degrees.

In a skillet or saucepan, melt butter over medium heat. Add garlic and cook for 1 minute, stirring constantly to prevent burning.

Add flour and stir to combine. Cook 1 minute. Add in the cream cheese and cook for 2 minutes.

Add 1 cup milk and stir to combine. Once thickened and bubbling, add the remaining cup of milk. Cook for 5 to 7 minutes, stirring often, until cream cheese has melted and sauce thickens.

Add Parmesan cheese. Stir to combine. Remove from heat.

Spray a 9 x 13 inch pan with non-stick cooking spray. Pour about 1/4 of the sauce into the bottom of the pan. Spread so the sauce covers the bottom of the dish.

Add frozen tortellini or ravioli to the baking dish in an even layer. Top pasta with chopped spinach and chicken so the pasta is covered.

Pour the rest of the sauce over the chicken and spread evenly around the baking dish. Sprinkle evenly with mozzarella cheese.

Bake at 350 degrees for 30 minutes, or until the sauce is bubbly and the pasta is cooked. Turn your oven to broil on HIGH and cook for 2-3 minutes, or until the top of the casserole is golden.

Remove from the oven and allow to sit 5 to 10 minutes. Serve warm with extra Parmesan if desired.