Preheat oven to 400 degrees F. Line a baking sheet with parchment paper.
Pierce potatoes with a fork; place potatoes onto the prepared baking sheet. Place into oven and bake until tender, about 1 hour. Let cool completely.
Cut in half; scoop flesh into a medium bowl and mash. Transfer 1 1/2 cups to a large bowl; stir in flour, ricotta, Parmesan, egg, 3/4 teaspoon salt and 1/4 teaspoon pepper.
Working on a lightly floured surface, divide dough into 6 equal pieces.
Roll each piece into an 18-inch long rope, about 1-inch in diameter, sprinkling with additional flour as needed to prevent sticking. Using a sharp knife, cut each rope into 3/4-inch bite-size pieces; transfer to baking sheet.
In a large pot of boiling salted water, cook gnocchi in batches until tender, stirring occasionally, about 2-3 minutes. Drain well using a slotted spoon and transfer to a clean rimmed baking sheet.