Preheat oven to 375 and lay parchment paper on baking sheet.
Place sausages on baking sheet and bake in preheated oven for 20-25 minutes. Remove and chop up into 1/2 inch slices. (Or desired size)
While sausage bakes heat olive oil in large skillet on stovetop and saute onions and peppers. Cook down until soft on med-high heat (takes about 20 minutes)
Add alfredo sauce, 1 can diced tomatoes and 1/2 cup water to veggies. Bring to a simmer and simmer for 5-10 minutes.
Add uncooked tortellini into a 9X13 baking dish. Pour sauce over tortellini and mix in sausage. [If freezing tortellini bake you will freeze the casserole prior to baking. See freezer directions below for the next step. If not freezing then continue on to step 6.]
Bake in oven 40-50 minutes or until tortellini is cooked and sauce is bubbling.
Let stand 15 minutes before servings and enjoy!-