Preheat the oven to 350° F. Line an 8x8 baking sheet with parchment paper and set aside.
In a large bowl, whisk together the oats, cocoa powder, baking powder, and salt. Pour in the milk, maple syrup, eggs, oil, and vanilla. Stir until everything is combined.
Pour the oat mixture into the baking pan and bake for 30-40 minutes, or until the center is set. Allow the oats to cool in the pan for a few minutes before serving.
Video
Notes
Make sure to use old fashioned/rolled oats or quick oats- do not use steel cut! They will not bake the same.
Line your baking sheet with parchment paper and leave a little overhang for easy removal after baking.