2 medium potatoes
1 Tbsp. butter
1/2 tsp salt
1 egg yolk
1 to 1-1/2 cups all-purpose flour
In covered pan, cook potatoes in boiling water for 25 to 30 minutes, drain. Peel potatoes.
In mixer bowl, beat hot potatoes, butter, and salt until smooth. By hand, stir in enough of the remaining flour to make a moderately stiff dough. Turn out on floured surface. Knead for 4 or 5 minutes.
With well floured hands, shape dough into balls, using about 1 Tbsp. dough for each ball. Crease the center of each ball with handle of a wooden spoon.
Cook, several at a time, in large amount of boiling salted water for 8 to 10 minutes. Remove; drain on paper towels.
Serve right away with your favorite sauce, pesto, or butter and cheese.