• Add the cooled mashed potatoes to a mixing bowl.
• Add the egg to the mashed potatoes and mix well.
• Add the flour to the egg and mashed potatoes and mix until a dough forms.
• Dump the dough onto a floured countertop and knead only enough to form a smooth dough. Do not overmix!
• Roll the dough into a log about 1/2 inch in diameter, or roll the dough out into a large circle of the same thickness.
• Cut the dough into little pillows. Optionally: Roll the pillows over the back of a fork or a gnocchi board to add ridges to the gnocchi.
• Boil the gnocchi in boiling salted water for 2-3 minutes or until they float to the top. OR, freeze the gnocchi using the instructions below.

To freeze gnocchi for later:

• After shaping the gnocchi, spread them out evenly on a baking sheet and place in the freezer until they are fully frozen—about 1-2 hours.
• When the gnocchi is firmly frozen, transfer them to a freezer bag or container to store until you are ready to eat.
• To prepare frozen gnocchi, simply remove them from the freezer and cook, from frozen, by boiling them in boiling salted water for 2-3 minutes or until they float to the top. Serve however you'd like!