Take Italian sausage out of casing and break up into large bowl. Add all ingredients except cubed cheese and mushrooms. Mix together really well. Using an ice cream scoop, scoop out a heaping amount of meat mixture.
This gives you an idea how small the mushrooms are, that is a baby portabello, which is the same size as the small white mushrooms, and the little brown one is what I used.
You will remove the stems from the mushrooms.
Form a ball out of the meat, then press a hole in center, not all the way through!!! Place the mushroom in the center and a pc. of cheese.
Fold meat over top and roll in hands for a good 10-15 seconds to seal the meatball good.
Bake at 325° for 40 min. Once sauce is ready, place meatballs in sauce if desired and simmer a few minutes longer. Serve with your favorite pasta.