Preheat oven to 150 °C. Line a square baking dish with baking paper.
Prepare chocolate
Gently heat ¼ cup coconut oil, ¼ cup maple syrup and 100 g dark chocolate in a small pot over low-medium heat, stirring continuously, until the chocolate is melted. Set aside to cool slightly.
Make chocolate batter
Drain and rinse 400 g black beans. Add the black beans to a food processor or blender and blend until very smooth, scraping down the sides as needed. Pour the cooled chocolate mixture into the food processor (reserve the pot) along with 1 tsp baking powder, 2 eggs and 1 tsp vanilla extract and blend until very smooth, scraping down the sides when needed to ensure all ingredients are well blended. (If using flour, stir to combine ingredients in a large bowl).
Bake brownie
Roughly chop 50 g dark chocolate into smaller chunks. Pour the chocolate batter into the prepared baking dish. Sprinkle the chopped chocolate over the top and gently stir into the batter. Bake in the oven for 20-25 minutes, until it's mostly set around the edges, but still slightly soft in the middle. Set aside to cool for 5 minutes.
Make caramel
Meanwhile, add ¼ cup coconut oil, 2 tbsp peanut butter and ¼ cup maple syrup to the cleaned reserved pot and gently heat, whisking continuously, until smooth. Add ½ tsp sea salt and 1 tsp vanilla extract and whisk to combine. Pour over the cooled brownie, using a spatula to spread it evenly over the surface. Place the brownie in the fridge to cool while you make the chocolate topping. Reserve the pot.
Make chocolate topping
Using the cleaned reserved pot, melt 100 g dark chocolate and 1 tbsp coconut oil on low heat stirring continuously until melted, smooth and glossy. Gently spread over the caramel layer of the brownie using a spatula or the back of a spoon. Place the brownie back in the fridge for at least 1 hour to set.
To serve
Use a hot sharp knife, and carefully slice into 16 squares.