Cook tortellini al dente, drain and set aside into a large mixing bowl.
Cut chicken into small chunks. Roll small balls out of ground Italian sausage.
Heat up a large cooking pan over medium heat and add some vegetable oil.
Cook chicken and sausage (seasoned with a little bit of salt) until just done and take it out into the bowl with tortellini. (Keep the juices from cooking meat in the pan, you will cook veggies in it.)
Dice tomatoes and onion and add it to the cooking pan. Saute for a few minutes.
Crush and chop garlic cloves and add it to the cooking pan. Mix and cook for about a minute.
Add pasta sauce, minced basil leaves, brown sugar, salt, and red pepper flakes. Stir everything and bring to simmer. Take off heat.
Preheat oven to 350 and lightly grease a casserole dish. (1.5 to 2 quart size will work well.)
Add grated Asiago, Parmesan, and Romano cheeses to the bowl with meat and tortellini. Mix well and add pasta sauce. Mix everything together.
Spread the mixture evenly in the casserole dish.
Top with Mozzarella cheese evenly and bake for about 15 minutes.