• Preheat the oven to 400 degrees. Spray one 12 cup nonstick mini doughnut pan with baking spray.
• In a mixing bowl, mix together the butter, milk, vanilla, and eggs.
• Sift together the flour, cornstarch, salt, and baking powder into butter and egg mixture. Stir until everything is combined.
• Spoon a ring of batter into each doughnut cup.
• Bake the doughnuts for about 8 minutes, or until the doughnuts spring back when touched. Remove the doughnuts right away and let them cool on a baking rack. Dip them into the glaze and top with sprinkles.

For the Chocolate Glaze:

• Heat an inch of water in the bottom of a double boiler. Bring it to a simmer, not a boil, and then add all the ingredients and stir until everything is melted. Dip the doughnuts into the warm glaze. If you don't have a double boiler, just a heat-proof bowl over a saucepan of simmering water.