Instructions

• Preheat the oven to 350°F (177°C). Adjust the oven rack to the lowest position. Line a 9x13-inch baking pan with foil, leaving about a 1-inch overhang on all sides, and spray the foil with nonstick cooking spray.
• In a large bowl, whisk together 1/3 cup Dutch-processed cocoa and 1½ teaspoons instant espresso (if using). Add 1/2 cup plus 2 tablespoons boiling water and whisk until smooth.
• Add 2 ounces finely chopped unsweetened chocolate to the cocoa mixture and whisk until the chocolate is fully melted and the mixture is smooth.
• Whisk in 4 tablespoons melted unsalted butter and 1/2 cup plus 2 tablespoons vegetable oil. The mixture may look curdled—this is normal.
• Whisk in 2 whole eggs, 2 egg yolks, and 2 teaspoons vanilla extract until the batter is smooth and homogeneous.
• Whisk in 2½ cups sugar until fully incorporated.
• Using a rubber spatula, fold in 1¾ cups all-purpose flour and ¾ teaspoon salt just until combined. Do not overmix.
• Fold in 6 ounces bittersweet chocolate cut into 1/2-inch pieces. Scrape the batter into the prepared pan and spread into an even layer.
• Bake on the lowest oven rack until a toothpick inserted about halfway between the edge and the center comes out with just a few moist crumbs attached, 30 to 35 minutes. Transfer the pan to a wire rack and cool completely in the pan.
• Make the crème de menthe filling: in a bowl with an electric mixer, beat 1/2 cup unsalted butter (at room temperature) and 3 ounces cream cheese (at room temperature) on medium speed until smooth and fluffy, about 2 minutes. Reduce speed to low and add 3 tablespoons green crème de menthe and a pinch of salt; blend until combined. Keeping the mixer on low, gradually add 2½ cups powdered sugar until incorporated, then increase speed to medium and beat until smooth and fluffy.
• Spread the crème de menthe mixture in an even layer over the cooled brownies. Transfer the pan to the refrigerator and chill for at least 30 minutes.
• Make the crème de cacao ganache: place 14 ounces finely chopped dark chocolate, 1/2 cup heavy cream, and 2 tablespoons unsalted butter in a heatproof bowl set over a small saucepan of barely simmering water (double boiler). Stir constantly until the chocolate and butter are completely melted and the mixture is smooth. Remove the bowl from the heat and stir in 1 tablespoon crème de cacao.
• Let the ganache cool to room temperature (it will thicken as it cools) until it is spreadable but not fully set. Use an offset spatula to spread an even layer of ganache over the chilled crème de menthe layer. Return the pan to the refrigerator and chill for at least 30 minutes more.
• Using the foil overhang, carefully lift the brownies from the pan. Cut into squares and serve. Store brownies in an airtight container at room temperature for up to 5 days.