Preheat oven to 350°F. In a food processor, blend red kidney beans until smooth. Add 1-2 tbsp of water if necessary. Empty into a large mixing bowl.
In the food processor, add dates and avocado with 1-2 Tbsp of date water. Blend until smooth. Empty into mixing bowl.
To the mixing bowl, add the flour, cocoa powder, white sugar, baking powder, salt, chocolate chips and optional walnuts and hemp hearts.
Mix until well incorporated. You may need to add 1-2 tbsp additional water if the batter is too thick.
Line the baking dish with parchment paper. Pour batter into baking dish and smooth top to make level. Sprinkle top with extra walnuts, hemp hearts and chocolate chips if desired.
Bake for 40-45 minutes ,ensuring the center is firm.