Preheat the oven to 375°F and spray a 9x13" casserole dish with non-stick spray.
Bring a large pot of water to a boil, then add the tortellini and broccoli. Cook 4 minutes, or until tortellini floats to the surface and broccoli is bright green in color. Drain in a colander and set aside.
Into a large, deep skillet over medium heat, add the butter. When the butter is melted, add garlic. Cook for 30 seconds, stirring frequently.
Add the flour, Italian seasoning, salt, and pepper. Whisk to incorporate with the butter.
Continue whisking while gradually pouring in the milk.
Bring the sauce just to a boil then reduce the heat to low.
Stir in the mozzarella and Parmesan cheeses. Continue cooking over low heat 2- 3 minutes, stirring frequently until the cheeses are melted and the consistency of the sauce is smooth.
Add the cooked tortellini and broccoli, stirring gently to coat.
Pour the mixture into the prepared casserole dish.
Sprinkle with crushed crackers.
Bake for 15 minutes then serve.