Preheat oven to 350 degrees. Line a 9x13” pan with foil and spray with cooking spray.
Mix butter, flour, and sugar in the bowl of an electric mixer fitted with the paddle attachment. Mix until the dough comes together, but it will still be a little crumbly.
Pour into pan and press with your fingers to make the crust.
Bake crust for 10 minutes. While it’s baking, make the brownies. Mix all brownie ingredients in a medium bowl and stir by hand until combined. Pour over hot crust.
Bake brownies for 21-23 minutes, or until a toothpick comes out clean 1 inch from the side of the pan. Cool completely before frosting.
When the brownies are cool, make the frosting. Beat melted butter and powdered sugar with a handheld mixer in a large bowl. Mix in vanilla and coffee and beat until smooth. Pour over brownies and spread evenly. Chill to set. The frosting will stay set in the refrigerator, and get softer as the brownies come to room temperature.
Makes 24 brownies.