• Preheat oven to 325°F (163°C). Line a 9×13-inch baking pan with parchment paper or grease it lightly. This prevents sticking and makes cleanup easier.

Brownie Base:

• Combine unsweetened chocolate and butter in a microwave-safe bowl. Microwave in 30-second intervals, stirring between each, until smooth. You can also melt it over a double boiler for better control.
• Whisk together granulated sugar, eggs, and vanilla extract together in mixing bowl until combined. Gradually add the melted chocolate mixture, stirring constantly to avoid cooking the eggs
• In a separate bowl, mix all-purpose flour, espresso powder (if using) and salt. Slowly incorporate the dry ingredients into the wet mixture, stirring until just combined to avoid overmixing.
• Pour the batter into your prepared pan and smooth it out with a spatula. Bake for 25-30 minutes or until a toothpick inserted in the center comes out mostly clean (a few crumbs are fine for a fudgy texture).

Peppermint Filling:

• Beat butter and powdered sugar together in a large bowl, gradually adding the heavy cream and peppermint extract or schnapps. Beat with a hand mixer until smooth. You want it thick, creamy, and spreadable.
• Spread over cooled brownie layer. Place in the refrigerator to chill, 30 to 60 minutes.

Chocolate Topping:

• Place semisweet chocolate chips, butter, and heavy cream in a medium bowl. Heat in the microwave for one minute, stir. Continue heating and stirring until chocolate is melted and mixture is smooth.
• Spread warm chocolate mixture over chilled bars. Sprinkle with crushed peppermint candies, if desired.
• Place back in the refrigerator until completely chilled.
• Cut the finished brownies into 22 even pieces, or as many as you would like. For clean cuts, use a sharp knife, wiping it clean with a damp cloth between cuts. For extra precision, dip the knife in warm water and dry it off before slicing.