Preheat oven to 350 degrees F. Line an 8×8 pan with parchment paper.
Make the brownie batter first. In a medium bowl, make the flax egg by combining the ground flaxseed and water. Set aside for 5 minutes to thicken. Then add the pumpkin puree, coconut sugar, coconut oil, cacao powder, salt, baking soda, and apple cider vinegar. Mix with a spatula until smooth and well combined. Add the oat flour in. Stir until just combined, careful not to over mix. Fold in the chocolate chips. Pour batter into the pan.
Next make the cookie dough batter. In a medium bowl, combine oat flour, almond flour, salt, and baking powder. Mix until well combined. Add the coconut sugar, maple syrup, coconut oil, vanilla, and almond milk. Mix with a spatula until well combined. Fold in the chocolate chips. Spread batter carefully over the brownie layer.
Bake for 30-40 minutes or until the top is set, slightly golden, and a toothpick comes out clean. Mine took about 37 minutes. Let it cool in the pan for 20 minutes. Then carefully lift it out using the parchment paper and place on a cooling rack to cool completely. Slice and enjoy!