Ingredients
2 cups all-purpose flour
1/4 cup unsweetened cocoa powder
1/2 teaspoon coarse salt
2 sticks unsalted butter, room temperature
1 cup sugar
2 teaspoons pure vanilla extract
1 tablespoon instant espresso powder
1/2 cup cacao nibs
Preparation
Whisk together flour, cocoa powder, and salt in a bowl. In another bowl, beat butter with a mixer on medium speed until fluffy, about 5 minutes. Gradually add sugar, beating until mixture is very light, about 2 minutes. Stir vanilla and espresso powder together in a small bowl; add to butter mixture. Scrape down sides of bowl and beat until combined and smooth, about 1 minute.
Add flour mixture and beat on low speed until dough just comes together, about 1 minute. Beat in cacao nibs. Press dough evenly into a 9-by-13-inch baking pan lined with parchment. Cover with plastic wrap and smooth top with hands or the bottom of a dry measuring cup. Refrigerate until firm, at least 1 hour and up to 1 day.
Preheat oven to 350 degrees. Use a paring knife to cut dough into 48 bars, 8 across short side and 6 down long side. Use a fork or skewer to poke holes in top of each bar.
Bake until set, 30 to 35 minutes. Let cool in pan on a wire rack 10 minutes, then recut bars. Let cool completely in pan before serving. Bars can be stored at room temperature up to 3 weeks.
