1. Heat oven to 425°F (220°C).
2. On a large sheet pan, toss gnocchi and mushrooms with olive oil, garlic, Italian seasoning, red pepper flakes, salt and pepper. Roast 15–18 minutes, stirring once, until gnocchi are puffed and mushrooms are browned.
3. Add spinach and Parmesan to the hot pan; toss until spinach wilts. Dot with butter and toss again for gloss.
4. Finish with a squeeze of lemon and extra Parm. Crack more black pepper over the top.