Combine ricotta, mascarpone, salt, pepper, and nutmeg (if desired) and blend well with a spoon or using a mixer on medium speed. Add the flour in one increment, slowly incorporating it with a spoon or with the mixer on low speed until flour is incorporated and dough just begins to pull off the sides of the bowl—about 30 seconds in a mixer. Do not overmix, as this leads to tough gnocchi.
Cut a portion of dough into workable, fist-size pieces. If it is slightly tacky, dust it with a little flour. Roll one piece into a half-inch thick tube. Lightly dust with flour and set aside. Repeat with remaining dough.
Fill a large pot with 2.5 gallons of water and place over high heat.
With your fingers (not your thumb), press into each of the dough rolls at about 1/2-inch increments. Using a bench scraper or knife, cut in between each of the fingerprints. Lightly toss with flour to prevent sticking.
Once the water reaches a rapid boil, add the gnocchi. Keeping the heat on high, quickly bring water back to a boil. When boiling, turn the heat down to medium and cook until all the gnocchi rise to the surface.
After gnocchi begin to float, allow them to boil 20 to 30 seconds longer, then use a slotted spoon to add them to a saucepan over medium heat without rinsing or draining. Pour about 3/4 cup of the cooking water into the pan. Add butter and sage, chives, or basil, keeping the pan moving to emulsify the butter into the water. Toss the gnocchi until sauce begins to look creamy. Remove from the heat, add pecorino, and serve.
Chef’s Note: Don’t need eight servings? Freeze some for later, or simply cut the recipe in half.