1 cup (120 grams) flour
1/2 teaspoon baking powder
1/2 teaspoon salt
1/2 cup (43 grams) unsweetened cocoa powder
2 teaspoons espresso powder
1 and 1/2 sticks (170 grams) unsalted butter
3 Tablespoons vegetable oil (35 grams)
1 and 1/2 cups (300 grams) granulated sugar, divided
2 large eggs plus 1 egg yolk
3/4 cup (128 grams) chocolate chips
Preheat oven to 350°F (175°C) and line a 9×9-inch baking pan with parchment paper. Spray it with non-stick baking spray and keep it aside.
In a large bowl, sift together baking powder, cocoa powder, salt, espresso powder and flour to make the dry mix.
In a saucepan, add butter, oil, and ½ cup of sugar, and heat on medium heat until the butter melts completely.
In a large mixing bowl, whisk eggs and the remaining sugar until well combined. Now slowly pour the warm butter mixture into the eggs gradually and whisk constantly.
Add the dry ingredients and chocolate chips to the mix and slowly stir with a spatula until combined. Do not overmix.
Pour the batter into the lined baking pan and bake for 30 minutes until the edges get firm and slightly cracked. Take the pan out, place it on a wire rack and let cool before slicing.