The zing of fresh lemon enhances both the peas' sweetness and the natural flavor of the spinach. The whole quick, creamy dish is bolstered by soft pillows of potato gnocchi.
Simmer peas with cream, red-pepper flakes, garlic, and 1/4 teaspoon salt in a 12-inch heavy skillet, covered, until tender, about 5 minutes.
Add spinach and cook over medium-low heat, uncovered, stirring, until wilted. Remove from heat and stir in lemon zest and juice.
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.
Add gnocchi to sauce with cheese and some of reserved cooking water and stir to coat. Thin with additional cooking water if necessary.