In a food processor, blend feta cheese and 3 tbsp heavy cream until smooth and creamy, creating whipped feta. If needed, add the rest of the heavy cream. Use a spoon shmear it on a plate. Set aside while you make the gnocchi. Or you can make this ahead of time and store in an airtight container — keep in the fridge for up to 3 days.
Cook the sweet potato gnocchi according to the package instructions or your homemade recipe. Drain and set aside.
In a skillet, melt unsalted butter over medium heat. Add fresh sage leaves and let them crisp up in the butter until fragrant. Add a pinch of salt.
Add the cooked sweet potato gnocchi to the skillet, tossing gently to coat with the brown butter and sage. Fry and allow the gnocchi to get a golden brown color.
Plate the fried sweet potato gnocchi on the feta and drizzle with the brown butter sage. Add a squeeze of lemon if desired.