For potatoes, prick skins with a fork. Bake in a 425 degree F oven for 40 to 60 minutes or until tender. (Or, cook whole, unpeeled potatoes in boiling water for 20 to 25 minutes or until tender. Drain.) When cool enough to handle, peel and cut up potatoes. Mash potatoes with a potato masher or run through a food mill or ricer.
In a medium bowl combine potatoes, chives or parsley, salt, and pepper. Stir with a fork until combined. Using a wooden spoon, stir in enough of the 3/4 to 1 cup flour to form dough into a ball.
On a lightly floured surface, knead in enough remaining flour to make a dough that is firm and not sticky (this will take about 3 minutes). Divide dough into 4 portions; divide each into 16 portions (64 total). Form dough into balls.
Place 1 ball at a time onto a floured fork press with finger to flatten slightly. (Gnocchi should have ridges on one side and a depression on the other.) Transfer to a baking sheet lined with waxed paper.
In a 3-quart saucepan cook the gnocchi, half at a time, in a large amount of gently boiling, lightly salted water for 1 to 2 minutes or until gnocchi rise to the top and have a bread like texture. Remove gnocchi with a slotted spoon. Keep warm.
For sauce, in a saucepan stir together the 2 tablespoons flour and the garlic powder. Gradually whisk in milk. Cook and stir over medium heat until bubbly. Cook and stir for 1 minute more. Stir in the 2 tablespoons basil and the prosciutto or ham. Heat through. To serve, stir together gnocchi and sauce. Sprinkle with cheese and additional basil. Serves 4.
Shape gnocchi as directed above. Cover and chill up to 12 hours.