Preheat oven to 425F and line baking sheet with parchment paper.
In a large bowl, add quartered brussels, shaved brussels, onion, and gnocchi.
In a glass measuring cup, whisk together olive oil, lemon zest and lemon juice, rosemary, garlic, salt, and pepper. Pour over veggies and gnocchi and then add in ¼ cup freshly grated parm and toss until fully coated. Put veggie mixture in the oven and bake for 10 minutes.
Remove veggies from oven, toss gently with a spatula, and then crumble sausage overtop in small bite size pieces. Put sheet pan back in oven and bake for 20 minutes. Broil for the last 3-4 minutes to get slighty crispy on top.
Remove from oven and top entire sheet pan with freshly grated parmesan cheese.
