In a mixing bowl, combine buttermilk, eggs, and the melted butter. Then add the flour, sugar, baking powder, baking soda, and salt. Stir until combined.
Line a 9x13 glass pan with parchment paper and spray with cooking spray. Evenly spread the batter in the pan. Sprinkle any desired ingredients (fruit or chocolate chips) on top of the batter before baking.
Bake at 400°F for 15 minutes. When a knife is inserted in and comes out clean, it's done. Top with anything you like: fruit, whipped cream, maple syrup, etc.