Ingredient:

• 6-1/2 cups all-purpose flour
• 3 teaspoons baking powder
• 1-1/2 teaspoons salt
• 1-1/2 cups cold butter
• 9 ounces sour cream
• 3 to 4 tablespoons water
• FILLING:
• 1 pound medium potatoes, peeled and cubed (about 2 cups)
• 1/4 cup butter, cubed
• 3 medium onions, finely chopped
• 1 teaspoon salt
• 1/4 teaspoon pepper
• 2 large eggs, divided use
• Sour cream, optional