Mint Chocolate Brownie Sandwiches with Creamy Creme de Menthe Filling

Brownie Cookie:

• 12 oz (340 g) semi-sweet chocolate chips, (1 bag)
• 4 Tbsp (57 g) butter
• 2 large eggs
• ⅔ cup (134 g) granulated sugar
• 1 tsp vanilla extract
• ¼ cup (30 g) all-purpose flour, sifted
• ¼ tsp baking powder, sifted

Creme De Menthe Buttercream:

• ½ cup (113 g) butter, room temperature
• 1 cup (120 g) powdered sugar
• 1 tsp pure creme de menthe extract
• green food coloring, optional
• green sugar crystals, optional

• In a small saucepan over low heat, melt the chocolate and butter together, stirring until smooth. The mixture will be thick but glossy. Set aside to cool slightly.
• In the bowl of a stand mixer fitted with the paddle attachment, beat the eggs, sugar and vanilla for about 15 minutes, until the mixture is pale and creamy.
• Add the sifted flour and baking powder, then pour in the chocolate mixture. Mix just until combined, scraping the bowl and paddle as needed.
• Scoop about 2 tablespoonfuls of dough per cookie (a #50 scoop works well) onto parchment-lined baking sheets, spacing them apart.
• Bake at 350°F (175°C) for 10–12 minutes, until the tops are puffed and cracked. Let the cookies cool completely on the trays.
• While the cookies cool, make the creme de menthe buttercream. In a large bowl, beat the room-temperature butter with the powdered sugar and creme de menthe extract until smooth. Add more extract if you want a stronger mint flavor, but avoid overdoing it. Tint the frosting with green food coloring if desired.
• Fit a pastry bag with the inside of a coupler (leave the band off), fill with the mint buttercream, and pipe onto the underside of one brownie cookie. Top with a second cookie, pressing gently and twisting slightly so the filling spreads to the edges without cracking the cookie. Dip the edges of the filling in green sugar crystals if using. Repeat with remaining cookies.