Prick the sweet potatoes all over and microwave until soft, about 7 minutes. Let them cool, then scoop out the flesh into a mixing bowl.

Add the ricotta cheese, egg, salt, and cayenne. Mix until smooth.

Gradually add the flour until a soft dough forms. The dough should be soft but not sticky.

Divide the dough into small portions. Roll each portion into ropes and cut into bite-sized pieces.

Bring a large pot of salted water to a boil. Cook the gnocchi in batches for 2 to 3 minutes, until they float, then lift them out with a slotted spoon and drain well.

In a skillet, melt butter and add fresh sage leaves. Fry gnocchi until golden brown.

Serve hot with a sprinkle of Parmesan cheese and extra sage.