Kosher or sea salt and freshly ground black pepper
1 tablespoon flour
cup butter, melted
Trim spinach and wash in several changes of water. Cook in a large pot of boiling
salted water over medium-high heat for 10 minutes; drain in a colander and cool
under cold running water.
Place spinach in a clean tea towel; squeeze until completely dry (dumplings will
fall apart during cooking if there is moisture on leaves). Finely chop.
Combine ricotta, egg yolks, 1 cup of the parmigiano-reggiano, and lemon zest
in a large mixing bowl.
Stir in spinach and season to taste with cayenne, nutmeg, and salt and pepper.
Add flour and stir just until combined.
Bring a large pot of salted water to a simmer over medium heat.
Wet hands (mixture will be sticky) and shape 1 tablespoon of mixture into a 1-inch
ball. Drop ball into simmering water and cook until it floats to the top. If ball
holds its shape, continue rolling remaining mixture. If ball falls apart, add another
1–2 teaspoons flour to mixture. Test again.
Cook dumplings in batches. As they float to the top, transfer to a serving dish
and cover with aluminum foil to keep warm.
Drizzle dumplings with butter and top with remaining parmigiano-reggiano.