Preheat the oven to 350°F (175°C).
In a large bowl, whisk together the melted coconut oil, hot cocoa granola butter, coconut sugar, egg (or flax egg), and non-dairy milk until well combined.
In a separate bowl, whisk together the oat flour, almond flour, cocoa powder, baking powder, and sea salt.
Gradually add the dry ingredients to the wet ingredients, mixing just until combined. Fold in chocolate chips.
Pour the batter into a greased, parchment-lined baking dish.
Bake for 20-23 minutes or until a toothpick inserted into the center comes out with a few moist crumbs.
Remove from the oven and top with marshmallows and additional chocolate chips.
Place back in the oven on broil for 1-2 minutes, or just until the marshmallows are toasted.
Cool for at least 15 minutes before slicing and serving. Enjoy!