Prep: 1. Boil water for gnocchi. 2. Smash garlic. 3. Chop onion. Make: 1. Simmer peas with cream, red-pepper flakes, garlic, onion and 1/4 teaspoon salt in a heavy skillet, covered, until tender, about 5 minutes. 2. Add spinach and cook over medium-low heat, uncovered, stirring, until wilted. Remove from heat and stir in lemon zest and juice. 3. Meanwhile, cook gnocchi in a pasta pot of boiling salted water (3 tablespoons salt for 6 quarts water) until al dente. Reserve 1/2 cup pasta-cooking water, then drain gnocchi. 4. Add gnocchi to sauce with cheese and some of reserved cooking water and stir to coat. Thin with additional cooking water if necessary.