In a bowl mix milk with vinegar and let sit for 5-10 minutes (instead of milk + vinegar you can use buttermilk). Then, add egg, melted butter and mix until combined.
In a separated bowl mix flour, sugar, baking soda and baking powder.
Combined wet mixture with dry mixture. Transfer the batter into a piping bag.
Heat a nonstick skillet or griddle over medium heat. Melt some butter or use oil, pipe small portion of batter into the pan.
Cook for about one minutes or until slightly golden. Flip and cook for 30 seconds more. Do not overcook.
Place mini pancakes in a bowl, drizzle some maple syrup and milk if desired.