Active Time

　　1 hr

　　Total Time

　　5 hr

　　These squares practically explode in the mouth with silky, fudgy chocolate and cool mint ganache.

　　

Ingredients

Makes about 6 dozen cookies

　　

For brownie layer

1 1/2 sticks (3/4 cup) unsalted butter

　　10 1/2 oz fine-quality bittersweet chocolate (not extra-bitter or unsweetened and no more than 60% cacao if marked), finely chopped

　　1 1/2 cups packed light brown sugar

　　3 large eggs, lightly beaten

　　1 1/4 teaspoons vanilla

　　3/4 cup all-purpose flour

　　1/4 cup plus 2 tablespoons unsweetened Dutch-process cocoa powder

　　3/4 teaspoon salt

　　

For mint ganache

1/2 cup heavy cream

　　10 oz fine-quality white chocolate, chopped

　　2 tablespoons green crème de menthe

　　1 teaspoon peppermint extract

　　

For chocolate ganache

1 cup heavy cream

　　10 oz fine-quality bittersweet chocolate (not unsweetened), finely chopped

　　

Special Equipment

an offset spatula

　　

Make brownie layer:

Step 1

Put oven rack in middle position and preheat oven to 375°F. Lightly butter a 13- by 9-inch baking pan and line with 2 crisscrossed sheets of foil, leaving a 2 inch overhang on all sides. Butter foil.

　　

Step 2

Melt butter and chocolate with brown sugar in a 3-quart heavy saucepan over moderate heat, stirring occasionally, until smooth. Remove from heat. Whisk in eggs and vanilla until combined. Whisk in flour, cocoa, and salt until just combined.

　　

Step 3

Spread batter evenly in baking pan and bake until set and a wooden pick inserted in center comes out with moist crumbs adhering, about 20 minutes. Cool completely in pan on a rack, about 1 1/2 hours.

　　

Make mint ganache:

Step 4

Bring cream to a simmer in a 2- to 3-quart saucepan and remove from heat. Pour over white chocolate in a bowl. Let stand 1 minute, then whisk until smooth. Stir in crème de menthe and extract and chill, covered, stirring occasionally, until thick, about 1 hour.

　　

Make chocolate ganache:

Step 5

Bring cream to a simmer in a 2- to 3-quart saucepan and remove from heat. Pour over bittersweet chocolate in a bowl. Let stand 1 minute, then whisk until smooth. Chill, covered, stirring occasionally, until thick, about 30 minutes.

　　

Assemble layers:

Step 6

Spread mint ganache over top of cooled brownie in a thin even layer using offset spatula, then chill until firm but still slightly sticky, about 30 minutes.

　　

Step 7

Spread chocolate ganache over mint and chill until firm, about 2 hours.

　　

Step 8

Lift dessert out of pan using foil overhang. Run a heavy knife under hot water and wipe dry, then trim edges of dessert (1/4 inch off each side). Cut dessert into squares and peel from foil.

　　Cooks'

　　· Squares keep, layered between sheets of wax paper or parchment, chilled in an airtight container 3 weeks. · We recommend Droste unsweetened cocoa and Lindt bittersweet chocolate for this particular recipe.