1. Preheat your oven to 175°C and line a square baking dish with parchment paper.

2. In a blender or food processor, blend the avocados until smooth and creamy.

3. In a mixing bowl, combine the avocado puree, cocoa powder, almond flour, coconut flour, erythritol, eggs, vanilla extract, baking powder, and salt. Mix well until all the ingredients are fully incorporated.

4. Pour the brownie batter into the prepared baking dish and spread it evenly.

5. If desired, sprinkle some sugar-free chocolate chips or chopped nuts on top of the batter.

6. Bake in the preheated oven for about 20-25 minutes or until a toothpick inserted into the center comes out with a few moist crumbs.

7. Remove from the oven and let the brownies cool completely in the baking dish before cutting into squares.

8. Serve and enjoy your delicious Keto Avocado Brownies!