http://thefamilyfeed.com/2012/10/05/black-bean-brownies-with-creamy-avocado-frosting/

Avacado Frosting: http://www.howsweeteats.com/2012/08/fudgy-avocado-brownies/
Black Bean Brownies: http://allrecipes.com/recipe/black-bean-brownies/#

Preheat oven to 350 degrees F (175 degrees C). Lightly grease an 8×8 square baking dish. Yields: 16 (small) brownies and enough frosting to cover the same. You have enough frosting for two batches so either cut the measures in half or save the rest in an airtight container, in the refrigerator for up to one week. It will not turn brown. Or, freeze for up to two months in an airtight container or freezer bag.

Ingredients:

Avocado Frosting:
1 large ripe, organic avocado
2 1/2 Cups powdered sugar
1/4 teaspoon pure vanilla extract

Black Bean Brownies:
1 (15.5 ounce) can organic black beans, rinsed and drained
3 eggs
3 Tbsp extra virgin olive oil
1/4 cup dutch-process cocoa powder
Pinch of Kosher salt
1 tsp. pure vanilla extract
3/4 cup organic granulated sugar
1 Tbsp espresso or 1 tsp. instant coffee (optional but suggested)
1/2 Cup bittersweet chocolate, chopped (optional)

Directions:

Avocado Frosting:
In the bowl of an electric mixer, fitted with a paddle attachment, beat the avocado at medium speed until creamy. Stop and scrape the sides of the bowl as needed. With the mixer on low speed, add in the vanilla then slowly add the powdered sugar, again stopping to scrape down the sides of the bowl as needed, until a smooth frosting forms. Wait for the brownies to completely cool to room temperature before frosting.

Black Bean Brownies:
Combine all ingredients into a food processor and process until completely smooth and creamy. Pour into the prepared baking dish and, if you choose, sprinkle the chopped chocolate over the top of the mixture. Bake until the top is dry and the edges start to pull away from the sides of the pan, about 30 minutes.