3/4 cup (1 1/2 sticks) unsalted butter, cut into pieces,plus more for pan
8 oz bittersweet chocolate, chopped
1 tsp pure vanilla extract
1 1/4 cup sugar
1/2 cup unsweetened cocoa powder
1/2 tsp instant espresso powder
1/4 tsp kosher salt
4 large eggs
3/4 cup all-purpose flour, spooned and leveled
1/4 cup PBfit Chocolate
1. Place a baking sheet on the middle rack of the oven and preheat to 350°F.
2. Butter an 8-by 8-inch baking pan. Line bottom and sides with parchment paper, leaving a 2-inch overhang on 2 sides; butter paper.
3. Melt butter in a medium saucepan over medium heat; remove from heat. Add chocolate, and stir until melted and smooth. Stir in vanilla. Add sugar and stir until mixture is smooth and shiny. Stir in cocoa, espresso, chocolate pbfit and salt; cool 10 minutes.
4. Whisk eggs into chocolate mixture until incorporated. Add flour and stir until smooth.
5. Transfer batter to prepared pan.
6. Bake until a toothpick inserted in the center comes out with moist crumbs attached, 35 to 40 minutes. Cool in pan on a wire rack.
7. Use paper to lift brownies from the pan. Remove paper and cut brownies into shapes or into 16 bars