Whisk together the flour, sugar, salt, baking soda and baking powder in a large bowl. Whisk in the buttermilk, eggs and melted butter until just combined.Heat a large pan or griddle over medium heat. Do not add the batter until the pan is hot. Spray with cooking spray. Use a 1/3 cup measure to scoop the batter onto the pan. Cook pancakes for about 2 minutes on each side. You will know they are ready to flip when the raw side has formed small bubbles all over.Serve hot. Freeze extras for up to 3 months.