A fine use for leftover mashed potatoes, croquettes can also be made with 3 cups Mashed Potatoes with Cabbage and Scallions.
Beat into:
      1 large egg
      2 cups Mashed Potatoes
And any of the following for flavor, if desired:
      1/2 cup sautéed diced onions or sliced mushrooms (optional)
      5 scallions, thinly sliced (optional)
      2 tablespoons chopped fresh thyme, fresh parsley, fresh marjoram, or fresh chives (optional)
Divide into 8 portions (2 per serving) and shape into small cakes. Dust lightly with:
      All-purpose flour
Dip in:
      1 large egg, lightly beaten
Then in:
      1 cup fresh breadcrumbs or 1/2 cup sesame seeds
Heat in a large nonstick skillet over medium-high heat:
      1 to 2 tablespoons butter, olive oil, or vegetable oil
Add the croquettes and fry, until nicely browned, about 5 minutes on each side. Drain on paper towels. Serve hot.