One 10-ounce box frozen chopped spinach, thawed
1 cup whole-milk ricotta cheese
2/3 cup freshly grated Parmesan cheese, plus 2 tablespoons for serving
1 egg yolk
2 tablespoons all-purpose flour, plus more for dusting
The gnocchi can be made ahead and frozen. Place the uncooked gnocchi in a single layer on a baking sheet tray and freeze for 30 minutes. Transfer to a resealable plastic bag, label and freeze for up to 4 months. Thaw to room temperature then proceed with boiling.