Preheat the oven to 350 degrees F / 180ºc. Line or grease a brownie pan.
In a blender, add non dairy milk, sugar, maple, vanilla, nut butter and oil and blend until the sugar and nut butter are mixed in.
Add the flours, baking powder, baking soda, salt and pulse for 2 to 3 seconds, Pulse twice to combine well into a smooth batter. Alternatively, combine the flours, baking powder, baking soda and salt in a bowl and pour the blended nut butter milk mixture into the bowl. Mix to make a smooth batter.
Pour the batter in the prepared pan. Tap to even it out.
Bake for 21 to 24 minutes or until a toothpick from the center comes out clean.
Cool for 10 minutes, then remove from the pan and cool on the wire rack for 15 minutes.
Make the glaze: Combine the chocolate non dairy milk, coconut oil in a saucepan over medium low heat. Stir frequently until most of the chocolate starts melting. Take off heat and stir until smooth.
Add the nut butter to the warm hot mixture and mix to combine until smooth. It will take a minute to mix in, depends on the nut butter.
Pour over the cake and spread using a spatula. Garnish with shaved chocolate or cocoa powder or coconut. Cool for 10 minutes. Then slice and serve with a cup of hot chocolate.