Preheat the oven to 325°F. Line an 8X8 square pan with parchment paper. Leave an extra piece from the side to make it easy to lift the brownies.
Melt the butter in the microwave and add the oil. Let cool down until you do the next step.
¾ cup Butter, ¼ cup Oil
In a medium-sized bowl, sift all the dry ingredients, including flour, cornstarch, salt, espresso powder, and cocoa powder
¾ cup All-purpose flour, 1½ tablespoon Corn starch, 1 tablespoon Espresso powder, ½ teaspoon Salt, 1 cup Cocoa powder
Set the stand mixer on whisk attachment and whisk the brown sugar, granulated sugar, eggs, egg yolk, and vanilla extract. This step should take about 3-4 minutes until the mixture is light and fluffy.
1½ cups Granulated sugar, ½ cup Brown sugar, packed, 3 Eggs, 1 Egg yolk, 1 tablespoon Vanilla extract
using a spatula, add the melted butter and oil mixture to the egg mixture and mix until just combined. DO NOT OVERMIX.
¾ cup Butter, ¼ cup Oil
Add the dry ingredients and the chocolate chips. DO NOT OVERMIX.
¾ cup All-purpose flour, 1½ tablespoon Corn starch, 1 cup Cocoa powder, 1 tablespoon Espresso powder, ½ teaspoon Salt
Pour the batter into the prepared pan and distribute evenly.
Bake for 20-25 minutes. The edges start to roll over and set. The center will be gooier, and that is okay. Brownies will keep baking as they cool down.
Remove from the oven and let cool completely. IT IS VERY IMPORTANT TO LET THE BROWNIES COOL DOWN BEFORE CUTTING THEM. Cutting the brownies early will leave you with a big brownie mess.