Preheat the oven to 400 degrees F. Place the potatoes on a baking sheet and bake until they're tender when poked with a fork. This should take about one hour. When the potatoes are done, immediately slice them open to let the steam out.
Bring a large pot of water to a boil; add a few pinches of salt. Scoop out the potato flesh and transfer it to a potato ricer or food mill. Push that thing down and repeat until you've passed all of the potato through the ricer. Sprinkle the potatoes with the salt and adjust according to your liking.
Sprinkle 1/4 cup of flour onto your clean counter or cutting board. Knead the potatoes with it, sprinkling in the remaining 1/4 cup flour, until the dough just comes together. If it's still pretty shaggy, add more flour one tablespoon at a time.
Now for the test! Pinch off a piece of dough and roll out into a tube. Cut it into a few pieces and boil it to make sure it holds its shape. If it falls apart in the water, this means you'll knead the dough a bit more. When right, the gnocchi will float to the top and look a little ragged, but hold together, when ready.
Roll the rest of the dough into ropes that are about 1/2-inch thick, then cut the ropes into 1/2-inch lengths. Transfer the gnocchi to a parchment-lined baking sheet, being sure the gnocchi don't touch each other.
Add the gnocchi to a boiling water a few at a time. Adjust the heat so the mixture doesn't boil too vigorously--it should be more like an aggressive simmer. When the gnocchi rise to the surface of the water, they're done. Remove them with a slotted spoon or mesh strainer and transfer them to your sauce or to a paper towel.