Cake Roll:

Coat 2 (15 x 10 x 1-inch) jellyroll pans with cooking spray; line with wax paper, and coat again with cooking spray. Set aside.

Beat eggs in a large mixing bowl at medium-high speed with an electric mixer 5 minutes. Add water, beating at low speed to blend. Gradually add cake mix, beating at low speed until moistened. Beat at medium-high speed 2 minutes. Divide batter in half, and spread batter evenly into prepared pans. (Layers will be thin.).

Bake each cake at 350 on the middle rack for 13 minutes or until cake springs back when touched in the center.

When cakes are done, immediately loosen from sides of pans. Sift 4 tablespoons cocoa (or more, as needed) either directly on top of cake or onto a cloth towel. (Do not use terry cloth to avoid sticking.) Turn each cake out onto the prepared towels. Peel off wax paper. Starting at narrow end, roll up each cake and towel together; place cakes, seam side down, in freezer for 15 minutes (recommended), in regrigerator for 1 hour or on wire racks. Cool cakes completely. Yield: 2 cake rolls.

Filling:

Beat whipping cream at medium-high speed with an electric mixer until soft peaks form. Fold in 3 tablespoons Grand Marnier and orange rind; set aside.

Unroll cake rolls; brush each lightly with remaining 3 tablespoons Grand Marnier. Spread each cake with half of whipped cream mixture. Reroll cakes without towels; place seam side down, on a baking sheet. Cover and freeze at least 1 hour (or up to 3 months, wrapped in foil.).

Dust cakes with cocoa, and cut into slices (cakes thaw almost as quickly as you can slice them.) Garnish, if desired. Yield: 5 to 6 servings each cake roll.

Sauce:

Heat half-and-half in a heavy saucepan over low heat. Stir in chocolate morsels, marshmallows, and salt. Cook over low heat, stirring constantly, until chocolate and marshmallows melt. Remove from heat; stir in Grand Marnier. Yield: 2 cups.

* 1/4 cup frozen orange juice concentrate, thawed and undiluted, may be substituted.