Step 1

Preheat the oven to 350°F. Lightly coat 24 cups of a mini-muffin tin with 1 tbsp melted butter.

Step 2

Puree the black beans in a blender or food processor until smooth and creamy. Measure 1/2 cup of black bean puree and reserve the remaining for use with tacos or nachos or as black bean dip.

Step 3

Prick the sweet potato a few times with a fork and microwave until it is completely soft and tender, about 7 minutes. Scoop out the flesh, set 1 cup in a large bowl, and add the black bean puree. Whisk in the remaining 2 tbsp melted butter, eggs, brown sugar, and vanilla.

Step 4

Add the chocolate chips to a small bowl and pour the hot coffee on top. Stir until melted, then add it to the sweet potato mixture.

Step 5

In another bowl, combine the cocoa powder, baking soda, and salt. Add the cocoa mixture to the sweet potato mixture and stir until just combined.

Step 6

Use a spoon to fill the muffin cups three-quarters full (you'll have enough batter for 24 mini-muffins). Bake for about 12 minutes, or until a cake tester inserted into the center of a brownie comes out with a few moist crumbs attached and the brownies resist light pressure. Let the brownies cool in the pan for about 5 minutes, then turn them out onto a wire rack to cool. Repeat with any remaining batter. The brownies will keep in an airtight container for up to 3 days.

Step 7

Serving size: 1 brownie