Preheat oven to 400 degrees Fahrenheit. Pierce each potato several times with a fork. Bake directly on the oven rack for 55-60 minutes.
Yes, you can microwave the potatoes instead. But, please, do not boil them! The extra water added through boiling will give you gluey gnocchi.
Allow to cool for 5-10 minutes. While still hot, halve the potato and scoop out the flesh. Pass through a potato ricer onto a clean floured work surface. Spread out the riced potato and let it steam off for about 5 minutes. This will help the potato dry out, which means you'll need less flour.
Gather the riced potato into a circle, then make a well/dent in the center. Into the well, add the beaten egg and salt.
Sprinkle 3/4 cup of flour over over the top. Using a bench scraper or your hands, fold everything together with light pressure until a dough just begins to form.
Add the rest of the flour one tablespoon at a time, until the dough no longer sticks to your hands.
Divide the dough into 6 equal pieces. On a lightly floured surface, roll each piece into a ¾-inch rope. Cut into 1-inch pieces.
At this point, you may want to test the gnocchi. Drop one piece in boiling water. If it falls apart, add 1 tablespoon of flour to the dough, re-form, and try again! This is especially helpful if it's your first time making gnocchi, because once you "get it," you'll be able to tell if the gnocchi dough is ready by it's feel.
If desired, shape each piece by rolling it over a fork or gnocchi board.
To cook the gnocchi, bring a large pot of heavily salted water to a boil. Test one gnocchi in the water. If it falls apart, try adding additional flour one tablespoon at a time. Cook gnocchi in batches — do not crowd the pot. Gnocchi are typically done in a few minutes. Remove with a slotted spoon 30 minutes after the float to the surface. I do not recommend pouring them in a colander to drain.
My cooking instructor once told me that your pasta water should be "salty like the sea." Under salting the water can make your gnocchi taste a little flat, no matter what sauce you put on it.
Toss immediately with your preferred sauce and serve warm.
Notes
If you don't have a potato ricer, that's okay! Just mash with a potato masher. You may have a few small lumps, but it is not that big of a deal. I do not recommend using a food processor. We want the cooked potato to feel fluffy before adding the other ingredients.