Make the flax egg by combining the flaxseeds with 2 tbsp water and setting aside for 5 minutes.
Preheat the oven to 180 degrees C (350 degrees F) and line a 10-inch square baking tin with a sheet of parchment paper. Leave some hanging over the edges, as this will make it easier to remove the cake from the tin.
Combine the soy flour, rice flour, tapioca flour, corn meal, and baking powder.
In a separate bowl, whisk together the maple syrup, peanut butter, apple cider vinegar and plant based milk. Continue whisking until the mixture is smooth and the ingredients are well-combined.
Add the wet ingredients to the dry and mix well using a spatula, before adding the flax egg and mixing again.
Transfer the batter to the tin and bake in the preheated oven for 22-25 minutes. Make sure not to over-bake it, as this will ruin the texture and dry out the cake. You'll know that the cake is done when it is golden brown on top and slightly crispy around the edges. A toothpick will also come out dry from the centre, with maybe a few crumbs but no batter.
MAKE THE GLAZE
Add the chocolate, maple syrup, peanut butter and coconut milk to a bowl and whisk until smooth.
ASSEMBLE THE CAKE
When the cake is ready, wait for it to cool down fully (around 15 minutes), then add the glaze and leave to set in the fridge for around 20 minutes more.