- 1 tablespoon vanilla extract
- 1 tablespoon instant espresso powder (optional)
- 2 1/2 cups all-purpose flour
- 3/4 cup unsweetened cocoa powder
- 1 tablespoon baking powder
- 1/2 teaspoon salt
- 1 cup mini chocolate chips
- 1 cup white sugar
- 3 eggs
- 1/2 cup vegetable oil
- Preheat oven to 375 degrees F (190 degrees C). Line 2 baking sheets with parchment paper.
- Combine vanilla extract and espresso powder in a small bowl; mix until espresso powder is dissolved.
- Sift flour, cocoa powder, baking powder, and salt into a bowl; mix in chocolate chips.
- Whisk vanilla mixture, sugar, eggs, and oil together in a large bowl. Add flour mixture; stir, by hand if needed, until dough comes together and is thick and stiff.
- Divide dough into 2 equal pieces and place onto the baking sheets. Shape each piece into a log as long as the baking sheet; press down with wet hands to about 1/2 inch thickness.
- Bake in the preheated oven until firm, about 25 minutes. Remove from oven and cool until easily handled, about 5 minutes.
- Move cooled logs to a cutting board and slice into 1/2-inch long slices with a serrated knife. Return the slices to the baking sheets, placing them on their sides.
- Bake until dry, about 6 minutes per side. Remove from oven and let cool until hardened on wire racks.