Preheat oven to 350°F. Microwave the chocolate and the butter for 2 minutes until the butter melts. Stir the mixture with a large wooden spoon until the chocolate melts and mixture becomes smooth.
Stir in sugar, eggs, mashed avocado and vanilla and mix until smooth. Stir in flour and mix until batter is smooth.
Pour the brownie batter into a greased 9 x 13 pan. Bake the brownies for about 20 minutes until toothpick inserted comes out clean.
While brownies are cooling, make the frosting. Add avocado, sugar and heavy cream into a blender and blend on high speed until batter is smooth, no avocado pieces remain and frosting is stiff enough for piping (it is still not as stiff as your typical buttercream of whipped cream frosting, but it should be stiff enough to hold a piped swirl).
After brownies are cooled, cut into squares and pipe with frosting.
The nutrition information provided are only estimates based on an online nutritional calculator. This is not a comprehensive list of all the nutrients in the recipe (i.e., does not include vitamins, cholesterol, etc). I am not a certified nutritionist. Please consult a nutritionist or doctor for accurate information and any dietary restrictions and concerns you may have.