Chill two medium mixing bowls and the beaters of an electric mixer. Place hazelnuts or almonds on a baking sheet in a single layer. Toast in a 350 degree F oven for 8 to 10 minutes, watching carefully and stirring so they don't burn. Cool. In a food processor bowl* (see blender note, below), cover and process toasted nuts and the 2/3 cup sugar until nuts are finely ground (do not overprocess). Add flour, butter, and salt. Process until combined. Add egg yolk. Process until thoroughly combined. Divide dough into four equal balls. Cover and chill two balls until needed.

Grease and lightly flour two baking sheets; place each sheet on a towel to prevent slipping while rolling dough. On each baking sheet, draw an 8-inch round with your finger using an 8-inch cake pan as a guide. On one of the prepared baking sheets, roll one portion of the dough to fit the circle, trimming edges of dough with a knife to make an even circle. Repeat with another portion of the dough on the second baking sheet. Score one dough round into 8 to 12 wedges, keeping circle intact. Sprinkle both rounds with sugar.

Bake the dough rounds in a 375 degree F oven for 10 to 12 minutes or until browned around the edges. Cool the cookies on baking sheets for 5 minutes. Cut the warm, scored cookie into wedges. Carefully transfer cookie and wedges to a wire rack; cool completely. Allow baking sheets to cool completely. Grease and flour baking sheets again. Repeat shaping and baking the two portions of dough except do not score either portion.

Use one of the chilled mixing bowls to prepare Chocolate Mousse; chill (for no more than 2 hours). In another chilled mixing bowl, beat whipping cream, the 1 tablespoon sugar, and vanilla on medium speed just until stiff peaks form. Spoon whipped cream into a pastry bag fitted with a large star tip.

Just before serving, place the chocolate (use the 3 ounces if also dipping berries) and shortening in a heavy small saucepan over low heat, stirring constantly until it is partially melted. Immediately remove from the heat and stir until smooth. Dip one long side of each cookie wedge into melted chocolate mixture. Set aside on waxed paper until chocolate is set. If desired, dip whole strawberries in remaining melted chocolate. (If your saucepan is not small, you may need additional chocolate to dip.)

To assemble torte, place a whole cookie on a serving platter. Spread with half of the Chocolate Mousse and top with half of the sliced strawberries. Place another cookie atop. Repeat with remaining Chocolate Mousse and sliced strawberries. Top with the remaining whole cookie. Pipe large dollops of the sweetened whipped cream atop torte, covering the whole top. Cover and chill about 2 hours to soften the cookies.

Arrange chocolate-dipped cookie wedges atop the sweetened whipped cream, placing chocolate-dipped edges up and tilting slightly in a pinwheel pattern. Pipe a large star of whipped cream in the center where the cookie wedges meet. If using chocolate-dipped strawberries, place between wedges and on top of the whipped cream star in the center. Serve immediately. With a serrated knife, cut into wedges. Makes 12 servings.

: In a blender container place half of the nuts. Cover and blend until finely ground. Transfer nuts to a mixing bowl; repeat with remaining nuts. In a mixing bowl beat butter and sugar until combined. Beat in egg yolk. Beat in ground nuts and half of the flour. Beat or stir in remaining flour. Continue as directed.

Bake and cool cookies. Layer the cookies, with waxed paper between each, in a covered storage container. Store at room temperature for 2 days or place in freezer containers and freeze for up to 1 month. If frozen, thaw the cookies before using.Chocolate Mousse: In a chilled mixing bowl combine 1/4 cup sugar and 3 tablespoons unsweetened cocoa powder. Add 1-1/2 cups whipping cream. Beat with the chilled beaters of an electric mixer on medium speed just until stiff peaks form. Chill until needed. Makes 3 cups.