Preheat oven to 350°F. Line a 9x9-inch baking dish with parchment paper and lightly spray with nonstick spray. Set aside.
Add the mashed avocado, melted chocolate chips, sugar, eggs, brown sugar, and vanilla to a large bowl and whisk to combine.
1 cup mashed avocados, ½ cup chocolate chips, ⅓ cup granulated sugar, 2 large eggs , 2 egg yolks, 3 tablespoons brown sugar, 2½ teaspoons pure vanilla extract
Add in the cocoa, flour, and baking soda and whisk until just incorporated.
⅔ cup unsweetened cocoa powder, ⅔ cup all-purpose flour, ½ teaspoon baking soda
Add the hot coffee and whisk to combine, then add the chocolate chips and fold in using a rubber spatula.
2 tablespoons brewed coffee, 1 cup chocolate chips
Transfer the batter to the prepared baking pan and top with extra chocolate chips if desired.
Place the pan into the preheated oven on the middle rack and bake for 40 minutes, or until a toothpick inserted into the middle comes out clean or with a few moist crumbs.
Once baked, remove from the oven and place on a wire cooling rack to cool.