Adapted ever-so-slightly from Cooking Light Quick Baking magazine. Makes 20.
2 Tbsp instant espresso
1/4 cup hot water
1/4 cup (1/2 stick) unsalted butter
1/4 cup semisweet chocolate chips
1-1/2 cups unbleached all-purpose flour
1-1/3 cups sugar
1/2 cup unsweetened cocoa
1 tsp baking powder
1/2 tsp salt
1 tsp pure vanilla extract
2 large eggs
Preheat oven to 350°F. Coat the bottom and sides of a 9-inch-square baking pan with baking spray, and set aside.
In a small glass measuring cup, microwave 1/4 cup of water on HIGH for 30 seconds. Stir in the instant espresso until it's dissolved, and set aside.
In another small glass measuring cup, microwave the butter and chocolate chips on HIGH for 1 minute. Stir until the chocolate is smooth, and set aside.
In a large mixing bowl, combine the flour, sugar, cocoa, baking powder and salt. Whisk together until well mixed. In a medium bowl, combine the coffee, egg-chocolate mixture, vanilla extract and eggs. Whisk together until well incorporated. Pour the wet mixture into the flour, and, with a rubber spatula, stir just until combined; the mixture will be very dry and stiff, but keep working with the spatula until all of the flour is moistened. Transfer the batter to the prepared baking pan, and spread it evenly to all corners of the pan.
Bake for 22 minutes. Remove the pan to a wire rack and let cool completely before serving.