Active Time

　　35 min

　　Total Time

　　3 hr

　　These frozen dessert bars are large enough to hold you through a double feature. Don't worry about them melting — they're just as delicious when they soften.

　　

Ingredients

Makes 8 generous servings

　　

For chocolate layer

Vegetable oil for greasing pan

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

　　1 stick (1/2 cup) cold unsalted butter, cut into pieces

　　1/4 cup granulated sugar

　　1/4 teaspoon salt

　　3 large eggs, lightly beaten

　　1 teaspoon vanilla

　　1 cup salted dry-roasted peanuts (4 oz)

　　

For peanut butter layer

4 oz cream cheese, softened

　　1/2 cup creamy peanut butter (not "natural")

　　3/4 cup confectioners sugar

　　1/4 teaspoon salt

　　1/2 cup chilled heavy cream

　　1 teaspoon vanilla

　　

For hot fudge sauce

1/3 cup heavy cream

　　3 tablespoons light corn syrup

　　3 tablespoons packed brown sugar

　　2 tablespoons Dutch-process unsweetened cocoa powder

　　1/4 teaspoon salt

　　3 1/2 oz fine-quality bittersweet chocolate (not unsweetened), chopped

　　1/2 teaspoon vanilla

　　

Make chocolate layer:

Step 1

Put oven rack in middle position and preheat oven to 350°F. Line a 9-inch square baking pan with foil, allowing 2 inches of foil to hang over 2 opposite ends of pan, and lightly brush foil (except overhang) with oil.

　　

Step 2

Melt chocolate with butter, sugar, and salt in a double boiler or a large metal bowl set over a pan of barely simmering water, whisking occasionally, until smooth. Remove top of double boiler or bowl from heat and whisk in eggs and vanilla, then stir in peanuts.

　　

Step 3

Pour batter into baking pan and bake until set and edges are slightly puffed, about 15 minutes. Transfer cake in pan to a rack to cool completely.

　　

Make peanut butter layer:

Step 4

Beat cream cheese, peanut butter, confectioners sugar, and salt in a bowl with an electric mixer at medium speed until combined well, about 4 minutes.

　　

Step 5

Beat cream with vanilla in a bowl with cleaned beaters at medium-high speed until it just holds stiff peaks, then gently fold into peanut butter mixture until just combined.

　　

Step 6

Spread mixture evenly on top of chocolate layer and freeze, pan covered with foil, until firm, about 2 hours.

　　

Make hot fudge sauce:

Step 7

Bring cream, syrup, sugar, cocoa, salt, and chocolate to a boil in a 1-quart heavy saucepan over moderate heat, stirring until chocolate is melted. Reduce heat and simmer, stirring frequently, until thickened, about 3 minutes, then remove from heat. Stir in vanilla until incorporated. Cool sauce to warm.

　　

To serve:

Step 8

Carefully lift cake from pan by grasping overhang. Trim 1/4 inch from edges of cake and discard, then cut into 8 bars. Peel off foil and serve bars with sauce.

　　Cooks' notes:

　　Hot fudge sauce can be made 1 week ahead and cooled completely, then chilled in an airtight container or jar. Reheat before using. Leftover bars can be frozen, individually wrapped in plastic wrap, up to 4 days.