Prick sweet potato all over with a sharp knife. Microwave until very soft, 5 to 7 minutes. Let sit until cool enough to handle.

Cut potato in half and scoop flesh into a bowl. Mash or blend until smooth. Add ricotta cheese, egg, kosher salt, and cayenne; mix with a spoon until smooth and combined. Stir in flour until mixture comes together into a sticky ball of dough, adding more flour as needed.

Transfer dough to a floured surface and knead gently, adding flour as needed, until no longer sticky. Divide into 8 equal portions. Roll each into a rope, about ½-inch thick, using flour as needed. Dust ropes with flour and cut with a bench scraper into ½-inch pieces. Transfer pieces onto a sheet pan and let dry on the pan for 15 to 20 minutes, or refrigerate until needed.

Make sauce: Cook bacon, stirring occasionally, in a skillet over medium heat until browned and crisp, 7 to 10 minutes. Add butter; cook and stir until lightly toasted, 2 to 3 minutes. Turn off heat and stir in rosemary. Set sauce aside.

Bring a large pot of salted water to a boil. Cook gnocchi in boiling water until they float to the top, 3 to 4 minutes. Use a slotted spoon to transfer gnocchi to sauce in the skillet.

Place the skillet over medium to medium-high heat; coat gnocchi with sauce, season with salt, and cook until heated through. Turn off heat and stir in 1 tablespoon Parmigiano-Reggiano cheese.

Transfer gnocchi to a warm serving bowl and top with remaining Parmigiano-Reggiano.