Ingredients

Makes about 80 truffles

　　

For hazelnut base

Unsweetened cocoa powder for dusting

　　1 cup hazelnuts, toasted , loose skins rubbed off with a kitchen towel, and cooled

　　3/4 cup all-purpose flour

　　1/2 cup sugar

　　1/2 teaspoon salt

　　1/2 stick ( 1/4 cup) unsalted butter

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

　　2 large whole eggs

　　

For ganache

2 large egg yolks

　　1 cup heavy cream

　　1/8 teaspoon salt

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

　　Special equipment: a small metal offset spatula

　　

Make hazelnut base:

Step 1

Preheat oven to 350°F. Butter bottom and sides of an 8-inch square metal baking pan, then dust with cocoa powder, knocking out excess.

　　

Step 2

Finely grind nuts in a food processor with flour, sugar, and salt.

　　

Step 3

Melt butter in a 2-quart saucepan, then remove from heat. Add chocolate and whisk until smooth. Add eggs 1 at a time, whisking until smooth. Stir in nut flour until just combined.

　　

Step 4

Spread batter evenly in baking pan and bake in middle of oven until top is firm and dry and a tester inserted into center comes out with crumbs adhering, 15 to 20 minutes. Cool completely in pan on a rack, at least 2 hours.

　　

Make ganache:

Step 5

Lightly beat yolks in a bowl. Bring cream with salt just to a boil in a small heavy saucepan, then add half of it to yolks in a slow stream, whisking constantly. Whisk yolk mixture into remaining cream and cook over low heat, whisking, until slightly thickened and an instant-read thermometer registers 170°F (do not let boil).

　　

Step 6

Remove from heat and add chocolate, whisking until smooth. Pour ganache over hazelnut base in pan, smoothing top with offset spatula, and chill, covered, until firm, at least 5 hours.

　　

Step 7

Cut into squares with a warmed thin knife, wiping off knife after each cut, and remove from pan while still cold.

　　

Step 8

Serve truffles cold or at room temperature.

　　Cooks' notes:

　　· Truffles can be chilled up to 1 week.

　　· Truffles can be frozen in pan, covered tightly with foil, 1 month.