Preheat oven to 350 degrees. Spray an 8x8inch baking dish with nonstick spray and set aside.
In a large mixing bowl whisk together eggs, brown sugar, baking powder, cinnamon, vanilla, salt and melted butter until there are no lumps. Stir in milk and then mix in oats.
If baking right away, bake for 30-35 minutes.
If preparing ahead of time, cover and refrigerate overnight. In the morning bake at 350 for 45 minutes.