Start by boiling unpeeled potatoes in salted water, until they are cooked. Let them cool down and peel them.
Pass the potato through a potato ricer (see notes). Collect the riced potato in a fountain shape on a floured surface.
Add the flour, egg, salt and Parmesan to the riced potato and make the dough. Do not overdo it and do not press it too hard (see notes).
With a pasta cutter, divide the dough ball into 8 parts.
Roll each part into a log, 1/2" to 3/4" in thickness. Cut each roll into 1/2" pieces.
Shape the gnocchi. press gently each dumpling on a fork or on a pasta board, to make the recognizable gnocchi imprint (see notes).
In a skillet, add 3 tablespoons of butter and few leaves of sage. Let it brown, being careful to not burn it (see notes).
Bring a pot of salted water to boil, and add the gnocchi. If everything worked, the gnocchi will float to the surface in one minute. Remove them from the water with a slotted spoon and place them on the skillet where you browned the butter.
Plate them and enjoy this Italian homemade delicacy!