Preheat the oven to 180°C and grease a baking tray.
In a bowl, mix the flaxseed meal with water and let it sit for 5 minutes to thicken.
In another bowl, combine the flour, cocoa powder, sugar, baking powder, and salt.
In a separate bowl, whisk together the melted coconut oil, plant-based milk, maple syrup, and vanilla extract.
Add the flaxseed mixture to the wet ingredients and mix well.
Pour the wet ingredients into the dry ingredients and stir until just combined.
Pour the batter into the prepared baking tray and spread evenly.
Bake for 25 minutes or until a toothpick comes out clean.
Let it cool before cutting into squares.