1. In a bowl, combine the milk and vinegar. Allow to sit for 5 minutes. 2. Combine the flour, sugar, baking powder, baking soda, and salt in a bowl. 3. Whisk the egg and melted butter into the milk, stirring until combined. Pour the wet ingredients into the dry ingredients and stir until mixed well. 4. Pour pancake batter into each muffin cup. Add the topping of your choice to each cup. 5. Place in a preheated oven, 350, and bake for about 12-15 minutes, or until golden brown.