Preheat the oven to 350 F (177 C). Line an 9 x 9 pan with parchment paper along the bottom and two sides.
In a microwave safe mixing bowl add the butter and 1 cup of chocolate chips. Heat in 30 second increments, stirring after each until the butter and chocolate are fully melted and mixed together. Whisk in the espresso powder.
1 cup (226 g) unsalted butter, sliced, 1½ cups chocolate chips, divided, 2 teaspoons espresso powder
In large mixing bowl whisk the eggs, sugar, light brown sugar, vanilla extract, peppermint extract and salt until smooth and well combined.
3 large eggs, room temperature, 1 cup (200 g) granulated sugar, ½ cup (100 g) light brown sugar, 1 teaspoon peppermint extract, 1 teaspoon vanilla extract , ½ teaspoon salt
Once the chocolate and butter mixture has cooled to warm to the touch, whisk the melted chocolate and butter mixture into the egg and sugar until smooth and well combined. Whisk in the cocoa powder and flour until smooth and glossy. Fold in the remaining ½ cup chocolate chips.
½ cup (60 g) Dutch processed cocoa powder, ¾ cup (90 g) all purpose flour
Evenly pour the brownie batter into the prepared pan. Bake the brownies for 25 - 35 minutes. Cool the brownie in the pan for 1 hour. Then transfer the brownies to chill and fully set in the fridge for 1 hour. While the brownies chill, make the peppermint frosting. In the bowl of stand mixer fitted with paddle attachment add the butter, powdered sugar and peppermint extract. Cream the the mixture together on medium speed for 2 - 3 minutes or until the mixture is smooth and well combined. Once the brownies are fully cooled and chilled, evenly spread the peppermint frosting on top of the brownies. ½ cup (113 g) unsalted butter, room temperature, 2½ cups (300 g) powdered sugar, ½ - 1 teaspoon peppermint extract
While the frosting sets on the brownies, make the chocolate glaze. Add chocolate and butter to a microwave safe bowl. Heat the chocolate and butter together for 30 seconds or until fully melted, stir until smooth and fully combined. Pour the melted chocolate on top of the peppermint frosting. Evenly spread the chocolate, top the chocolate with crushed peppermint candy. Return the brownies to the fridge for 30 minutes to fully set the chocolate and peppermint candy. 4 oz. dark chocolate chips or chopped chocolate, 3 tablespoons unsalted butter, sliced, ¼ - ½ cup crushed peppermint candy
Remove the brownies from the fridge to slice and serve. For the cleanest brownie slices, use a knife that is as long or almost as long as the brownies. Press firmly down and gently pull the knife up. Wipe the knife clean before repeating any additional cuts for the brownie slices.