Place a rack in bottom third of oven; preheat to 400°.
Toss onion, garlic, gnocchi, olive oil, salt, red pepper flakes, and black pepper on a rimmed baking sheet to combine.
Create a little open space on one side. Finely grate lemon zest over gnocchi mixture; cut lemons into wedges and set aside for serving.
Crumble sausage in about 1" pieces onto open space on baking sheet.
Bake, tossing halfway through to evenly coat everything in oil again, until sausage and gnocchi are browned and crisp, 35–45 minutes.
Add kale to baking sheet and toss with tongs or 2 flat metal spatulas to coat in oil.
Bake until kale is tender, 6–10 minutes.
Remove gnocchi mixture from oven and scatter reserved lemon wedges around. Top with finely grated Parmesan if desired.
Tags: bonappetit, bon-appetit, bon appetit, dinner, gnocchi, greens, main, onepot, one-pot, one pot, pork, quick, sausage, sheet-pan-dinner
https://www.bonappetit.com/recipe/sheet-pan-gnocchi-spicy-sausage-broccoli-rabe