Combine ricotta, Parmigiano Reggiano, eggs, salt, and, if using, a few gratings of nutmeg in a large bowl. Mix thoroughly until smooth. Fold in flour with a spatula until well combined. The mixture should hold together but still be slightly tacky. If needed, add another tablespoon of flour.
On a lightly floured work surface, knead dough briefly and with a light touch, just until the mixture is uniform and there are no visible streaks of flour.
Dust work surface and dough with flour. Cut dough into thick slices (roughly the width of two fingers) using a bench scraper or sharp knife.
Dust a piece of dough with flour and gently roll it back and forth to create a smooth exterior. Continue rolling dough outward into a thick rope, about ¾-inch diameter. If dough gets sticky, dust with more flour. Continue with remaining dough slices.
Cut each rope into bite-size pillows, roughly 1 inch in length.
Line a baking sheet with parchment paper and dust with flour. Closely arrange gnocchi in a single layer on the prepared sheet without touching. (Finished gnocchi can sit at room temperature or uncovered in the refrigerator for up to 2 hours.)
Fill a large pot roughly two-thirds full with water and bring to a boil. Season generously with salt.
Using a spider sieve or slotted spoon, carefully lower gnocchi into water and cook until they float to the surface, about a couple of minutes, plus an extra 30 seconds. Transfer gnocchi to a large skillet filled with sauce of choice.