Chocolate-Pecan Crumb Crust
1 (2 ounce) round tablet Mexican
    table chocolate (such as Ibarra)
2 (1 ounce) squares semisweet chocolate
10 double graham crackers
1 cup pecan halves
2 teaspoons cinnamon
3 tablespoons brown sugar
4 tablespoons unsalted butter

Set oven rack in the middle of the oven and preheat oven to 400 degrees F.

Chop chocolate and drop through feed tube of a running food processor or blender. Add graham crackers and pecans and process until they are fine crumbs. Pour crumbs into a 10- or 12-inch diameter springform pan. Stir in cinnamon and brown sugar. Add melted butter and, using your fingers, quickly mash the mixture until the crumbs hold together. Use your knuckles to press up the sides, then press over bottom of pan. Bake 10 minutes. Cool.

Mascarpone Filling
1 tablespoon unflavored gelatine
1/4 cup cold water
1 1/2 pounds mascarpone cheese
24 ounces cream cheese, softened
1 cup granulated sugar
2 tablespoons lemon juice
1 1/2 tablespoons vanilla extract
1 1/2 cups cream

Dissolve gelatin in water in a small bowl, then set aside to soften for 5 minutes. To keep gelatine liquefied, set bowl in a larger bowl of hot water.

Beat mascarpone and cream cheese at high speed with an electric mixer until fluffy. Gradually pour in sugar while continuing to beat. At medium speed, beat in lemon juice and vanilla extract. Remove bowl from mixer and, using a large rubber spatula, quickly fold gelatine into cheese mixture.

In a cold bowl and with cold beaters, whip cream to stiff peaks. Fold a scoop of cream into the mascarpone mixture to lighten it and make it easier to blend with the cream. Then fold remaining cream into the cheese base. Pour into cooled crust. Cover well with plastic wrap and chill at least 4 hours.

Decorate with shaved chocolate and more whipped cream piped at intervals around the rim of the cake. Slice wedges with a knife dipped in a tall glass of hot water, then wiped dry.

Makes 16 servings.