Place the ricotta in a fine-mesh sieve or cheesecloth and let it drain for 15 minutes to remove excess moisture.
In a medium bowl, combine the strained ricotta, egg, parmesan cheese, sea salt, black pepper, and ground nutmeg until smooth.
Gradually fold in the flour until a soft, slightly sticky dough forms, being careful not to overwork it.
Turn the dough onto a lightly floured surface and divide into four portions, rolling each into a long rope about half an inch thick.
Cut the ropes into one-inch pieces and use a fork to create light indentations on each gnocchi.
Bring a large pot of salted water to a gentle boil and drop the gnocchi in, cooking until they float to the surface, then remove with a slotted spoon.
In a large skillet over medium heat, melt the butter and add the sage leaves, cooking until the butter begins to brown and the sage is crisp.
Add the boiled gnocchi to the skillet and sear for 1-2 minutes per side until they develop a light golden crust.
Toss gently to coat in the sage butter and serve immediately with an extra sprinkle of black pepper.