Preheat the oven to 350 degrees.  Spray an 8×8-inch baking pan with cooking spray.  Set aside.

In a microwavable-safe bowl, melt ¾ cup of chocolate chips in 30-second intervals, stirring after each interval until melted and smooth.  Set the bowl aside to cool for a few minutes.

Meanwhile, cut the avocados in half and use a spoon to scoop out the flesh.  Place the avocado in the bowl of an electric mixer.

Add the sugar to the bowl and beat together with the avocado until creamy.

Stir in the melted chocolate.

Beat the eggs, one at a time, into the avocado mixture.

Beat in the vanilla and espresso powder.

While the avocado and eggs are beating together, combine the dry ingredients in a small bowl.

Slowly add the dry ingredients to the avocado mixture until just combined.

Fold in the remaining chocolate chips.

Spoon the batter into the prepared pan.

Bake for 35 minutes until the brownies are set, but still, look fudgy.

Place the pan on a wire rack to cool completely.

If using, place the prepared chocolate frosting into a glass measuring cup.  Microwave on 50% power until liquified.  Use a spoon to drizzle the frosting over the brownies.

Use a knife to cut them into nine squares.