In a small skillet, heat the olive oil over medium heat until hot, but not smoking. Add the fresh sage leaves to the butter and let them crisp for about 1 minute in the hot oil. Transfer the sage to a plate lined with paper towels to drain. Sprinkle with salt and set aside.
Bring a small pan of water to a boil. Add a teaspon of salt and wait for minute until the salt dissolves in the boiling water. Reduce heat to a rapid simmer and add the sweet potato gnocchi. Cook the gnocchi until they start to float to the top of the pan. Drain the water from the pan and set aside.
In a medium skillet, heat the butter over medium to medium-low heat (depending on how hot your stove runs, mine runs hot), stirring constantly. The butter will melt, and begin to sputter a bit, then it will start to get foamy.
Continue stirring, and checking the milk solids (the specks in the bottom of the pan) they will start to turn golden and then brown and the butter smells nutty and toasty. This should take about 4-6 minutes. Don't keep the butter on the stove too long because those specks can easily burn and turn bitter.
Remove the butter from the heat and add the cooked gnocchi to the pan. Gently toss the gnocchi in the browned butter to coat. Sprinkle with fresh nutmeg and half of the parmesan cheese and toss again to combine.
Transfer the sweet potato gnocchi to a serving platter. Top with remaining parmesan cheese. Crumble or toss the crispy sage leaves over the dish and serve.