This is such a simple "recipe" (I rarely measure, so my recipes tend not to be what most think of as a recipe.)
Cooked rigatoni ( I used 4 boxes)
Spagetti sauce ( I used 2 large jars)
Alfredo sauce ( I used about half a gallon of it- I make my own. Our milk is fresh from the dairy, and includes a good bit of cream in it)
Mushrooms, peppers, onions, and cooked hot sausage, optional (saute the onions, peppers, and mushrooms first)
Mix, bake. Optional- top with cheese before baking.
I made 3 heaping full 9x13 pans... i think one small jar of alfredo sauce from the pasta sauce aisle, mixed with one equally sized jar of spaghetti sauce, and one box of pasta, would nicely fill one 9x13 pan.
This freezes well! I first learned the recipe at an Apples Of Gold meeting, where the woman teaching us had learned it from a woman in our church who brought it to her after a funeral. It's a great meal to keep in the freezer and pull out to warm up and take to someone.