Over medium heat, add oil to a large skillet. Add in chopped squash, garlic, and diced onion. Season with salt & pepper and pan fry stirring ocassionally until tender, about 10 minutes.
Bring a large stockpot of water to a boil and add 1/4 tsp of salt to it for flavor. Add your jumbo shells and boil until al dente. Using the collander, drain hot water from the shells and rinse in cool water. Drain any additional water from the shells before stuffing.
In a food processor, add small pieces of Galbani® Mozzarella cheese, and process until finely shredded.
Add your ricotta cheese, 1/2 the mozzarella cheese, and sauteed vegetables to a large mixing bowl, and stir to combine.
Add 26 ounces of pasta sauce to the bottom of your 11 x 13 pan.
Using a tablespoon, generously fill each shell with filling, and add shells directly on top of the sauce. Sprinkle shells with additional cheese and bake for 20 minutes covered. At the 20-minute mark, remove the foil, and bake for an additional 10 minutes uncovered. Sprinkle dish with fresh parsley before serving.