Drain a can of black beans and rinse thoroughly until the water runs clear. Return the black beans back to the can and fill with water. Puree the beans and water. Set aside.
In a large bowl, mix flour, sugar, cocoa powder, coffee power, salt and baking powder. Add the black bean puree, vanilla and stout to the dry ingredients and stir just until incorporated. Don't over mix.
Pour batter into a greased 9×13 pan. Bake for 25-30 minutes, rotating the pan around halfway through. They should be almost firm in the center.
Let brownies cool completely then cut into 24 squares.
Notes
Tips for storing
Cool completely before slicing, warm brownies crumble more.
Store airtight at room temp for 3 to 4 days for the best texture.
Refrigerate up to 7 days if your kitchen runs warm, let slices sit 15 minutes before eating.
Freeze sliced brownies for up to 3 months, wrap individually for easy grab-and-thaw.
Refresh: warm a slice for 10 to 15 seconds in the microwave for a fudgier bite.