01 - Preheat the oven to 350°F and grease a 9 x 9 inch baking dish to prevent sticking.
02 - In a large mixing bowl, whisk together rolled oats, baking powder, ground cinnamon, and salt.
03 - In a separate bowl, whisk together eggs, maple syrup or honey, melted coconut oil or butter, vanilla extract, and milk until thoroughly blended.
04 - Pour the wet mixture over the dry ingredients and stir until fully combined.
05 - Fold in the chopped nuts, dried fruit, or berries if desired.
06 - Transfer the batter into the prepared baking dish and spread evenly.
07 - Bake for 35 to 40 minutes, or until the top is golden brown and the center is set.
08 - Allow to cool for several minutes before slicing. Serve warm or at room temperature.