Cook Jumbo Shells according to package
While shells are cooking, take Italian Sausage out of casings. Crumble up sausage and cook.
Use spaghetti sauce of your choice. I use the family size Ragu Spaghetti sauce or two of the next to largest size. Here add what ever you would like, I always add more spices like 1 teaspoon basil, 1 teaspoon oregano, garlic, and onion powder to taste. Let simmer for about 30 minutes for herbs to cook.
Drain shells and set aside when done. Drain Italian sausage and add about 1 to 2 cups of cheese. My family likes lots of cheese so I use about 2 cups. I chop up some mushrooms and add to the meat mixture as well.
Pour some of the spaghetti sauce in the bottom of 9x13 baking dish, enough to cover the bottom. Mix some of the spag sauce in the meat mixture, but not where it is runny though. Take the meat mixture and stuff the jumbo shells. Place stuffed shells on top of the sauce in baking dish. After stuffing all the shells and they are in the baking dish, pour more spaghetti sauce over the noodles and then a layer of cheese. Bake 350 for about 20 minutes.
I am sorry there are not exact measurements concerning the sauce. I just pour and say that looks right.