1 2/3 cups all-purpose flour
1/2 cup unsweetened cocoa powder
1/2 teaspoons baking soda
1/4 teaspoon salt
1 1/2 sticks (12 tablespoons) of unsalted butter, melted and cooled
1 cup loosely brown sugar
1/2 cup granulated sugar
1 egg + 1 egg yolk, at room temperature
2 teaspoons vanilla extract
1 cup dark chocolate chips

peppermint pattie cream
2 cups powdered sugar
1 1/2 tablespoons unsalted butter, softened
3 tablespoons evaporated milk
1/4 teaspoon vegetable oil
1/4 teaspoon vanilla extract
1/4 teaspoon peppermint extract

ganache
3.5 ounces dark chocolate, chopped
2.5 tablespoons heavy cream