Process eggs in blender or processor at high for 1 minute. With motor running, gradually add milk, then flour; blend 30 seconds longer. Melt Butter in 10" oven safe skillet(wrap handle with foil) or a shallow baking dish in preheated 425 degree oven. Pour half of the batter into hot butter. Bake at 425 degree 20 minutes or until puffy and golden. Spoon blueberry sauce( recipe follows) into center of baked Dutch Baby. Sprinkle with powder sugar. Repeat with remaining batter. Cut in wedges to serve. Makes 6 servings. Blueberry Sauce: Rinse and drain berries, add water and heat until warm. Combine sugar, cornstarch and salt; add to berries. Cook and stir until thickened. Add lemon juice. Cool if desired before serving on Dutch Baby. This would also be good with Peaches or Apples cooked and thickened the same as the Berries. And served warm.