In large pot, boil about 20 (1/2 box) jumbo shells for about 8 min. You want them to be undercooked. Drain and rinse shells, then set aside.
Preheat oven to 350.
In large pan, add diced onion into 1 tbsp of olive oil and cook until transparent.
Add ground sausage and cook using chopper break up meat.
When sausage is browned, add garlic and cook additional 2-3 minutes, until garlic is fragrant and sausage is cooked.
Remove sausage from heat and pour into bowl. Let cool for a couple of minutes.
Add 1 cup of ricotta cheese to the meat, and stir to combine.
In casserole dish, cover bottom with a layer of sauce, so that your noodles don't stick to the bottom.
Use soup spoon to scoop meat mixture into shells and arrange in casserole dish.
Pour desired amount of sauce over top of filled shells.
Top with 1 cup of mozzarella cheese.
Bake in oven at 350 for about 30 min. Until sauce is bubbly and cheese is melted.
Serve immediately.
