1. Prepare GRAHAM CRUMB CRUST. Heat oven to 450°F.
2. Beat cream cheese and 3/4 cup sugar in large bowl until well blended. Gradually add flour; beat until blended. Add sour cream, 1-1/2 teaspoons vanilla, almond extract and eggs; beat until blended. Stir together cocoa and remaining 1/4 cup sugar in medium bowl. Add 1-1/2 cups cream cheese mixture and remaining 1/2 teaspoon vanilla; beat until smooth. Stir in butter. Pour vanilla mixture over prepared crust. Drop spoonfuls of chocolate mixture over top. Using narrow spatula or knife, swirl gently through mixtures to marble.
3. Bake 10 minutes. Reduce oven temperature to 300°F; continue baking 40 minutes. Cool completely in pan on wire rack. Cover; refrigerate at least 6 hours. Cut into squares. Refrigerate leftover dessert. About 24 servings.
GRAHAM CRUMB CRUST: Stir together 1-1/2 cups graham cracker crumbs, 1/3 cup melted butter or margarine and 3 tablespoons sugar Press mixture onto bottom of 13x9x2-inch baking pan.