Bring a medium pot of salted water to a boil.
Heat a pan over medium high heat, add 1 tablespoon oil and heat a little before adding butter. When butter melts and begins to sizzle, add sage leaves (in batches, so you don’t crowd the pan) and cook until dark brown and crisp, 20-30 seconds. Use a slotted spoon to transfer them quickly to a lined plate, and sprinkle generously with coarse salt.
Put the pan back on medium heat, add a tablespoon of olive oil, and then greens; cook for four to five minutes, stirring until wilted.
Add gnocchi to boiling water and cook until they rise to the surface, about two-and-a-half minutes. Remove gnocchi with a slotted spoon and add straight to pan with greens. Save some of pasta cooking water.
Add most of cheese and lemon zest to gnocchi and toss well; add ¼ cup cooking water and reduce to a thick sauce. Toss in crispy sage and season with sea salt and pepper, to taste. Divide gnocchi between two plates, sprinkle with remaining cheese and finish with a drizzle of olive oil.