01 -
Preheat your oven to 350°F (175°C). Generously grease a 24-cup mini muffin pan with softened butter, making sure to coat all the edges and crevices.
02 -
Create a double boiler by placing a small bowl over a saucepan with about an inch of simmering water (make sure the bowl doesn't touch the water). Add the bittersweet chocolate and oil to the bowl, stirring frequently until completely melted and smooth. Remove from heat and set aside to cool slightly.
03 -
In a large bowl, combine the granulated sugar, brown sugar, room temperature eggs, and vanilla extract. Using an electric mixer, beat on high speed for a full 5-6 minutes. This step is crucial - the mixture should double in volume and become pale and fluffy, creating that signature shiny brownie top.
04 -
With the mixer on low speed, slowly pour the cooled chocolate-oil mixture into the whipped egg mixture. Mix until fully incorporated, scraping down the sides of the bowl as needed.
05 -
Add the flour, Dutch process cocoa powder, black cocoa powder, espresso powder, and salt to the bowl. Mix on low speed just until mostly combined - a few streaks of flour are fine at this stage to avoid overmixing.
06 -
Add the roughly chopped bittersweet chocolate to the batter and gently fold it in with a spatula until evenly distributed. The batter will be quite thick and fudgy.
07 -
Using a cookie scoop or spoon, fill each cavity of the prepared mini muffin pan about ¾ full with brownie batter. Don't overfill or they'll overflow during baking.
08 -
Bake in the preheated oven for 15-18 minutes. The brownies are done when a toothpick inserted in the center comes out with a few moist crumbs (not wet batter). Be careful not to overbake or they'll lose their fudgy texture.
09 -
Allow the brownie bites to cool in the pan for about 5 minutes before carefully removing them. A small offset spatula can help if needed. Repeat the process with remaining batter until all brownie bites are baked.