Beat cake mix, 1/2 cup oil, 1 1/3 cups water, and 3 eggs at low speed with an electric mixer 1 minute, scraping bowl constantly. Pour batter into 2 (9-inch) round cakepans coated with butter-flavored cooking spray. Bake at 350º for 28 minutes or until a wooden pick inserted in center comes out clean. Cool in pans 10 minutes. Remove from pans, and cool completely on wire racks.
Stir together brownie mix, remaining 1/2 cup oil, 2 eggs, and 3 tablespoons water in a medium bowl until well blended. Spread in a 9-inch round cakepan coated with cooking spray. Bake at 350° for 35 minutes. Cool completely in pan; run a knife around pan to loosen.
Bake cookies according to package directions at 350° for 10 minutes. (Cookies will be soft.) Cool cookies on baking sheet 2 minutes before removing from baking sheet. Remove cookies to wire racks; cool completely.
Stir together flour and 1 tablespoon cocoa. Rub shortening and 1/3 cup sugar together in a medium bowl with back of a wooden spoon until blended. Gradually add milk, vanilla, and flour mixture, beating until smooth. Pour into a 9-inch round cakepan coated with cooking spray.
Stir together 1/2 cup brown sugar and remaining 2 tablespoons cocoa until blended; sprinkle over batter. Carefully pour boiling water over sugar mixture. (Do not stir.) Bake at 350° for 40 minutes or until top looks thickened and set. Cool pudding cake completely in pan.
Rinse strawberries, and pat dry. Place 1 cup chocolate morsels in a small bowl. Microwave at HIGH 1 minute; stir until smooth. Carefully dip strawberries in chocolate to coat. Place on a large plate covered with wax paper. Chill until chocolate is firm.
Place brownie layer on a serving plate. Loosen edges of pudding cake with a narrow flexible spatula, and invert onto brownie layer. (Don't worry if pudding cake layer doesn't come out of pan in one piece. Carefully place pieces together in 1 layer on top of brownie layer. When the cake is assembled, this layer resembles frosting between the layers.)
Place 1 cake layer over pudding cake layer; press gently. Thinly spread cake layer with frosting. Place about 5 cookies in a single layer over frosting. Thinly spread bottoms of remaining cookies with frosting. Place cookies, frosted side down, on top of each other in even layers. (Do not allow cookies to extend beyond edges of cake layer. Trim cookies with scissors if necessary, so they do not extend beyond edges.) Spread top cookie layer with about 1/2 cup frosting (you should have a little more than 1 can of frosting left). Place remaining cake layer over frosting, pressing down gently. Thinly frost top of cake layer and sides of all layers with remaining frosting. Sprinkle remaining chocolate morsels on cake. Cover and chill at least 2 hours.
Before serving, sift powdered sugar over morsels. Arrange chocolate-covered strawberries on top of cake. Serve with Strawberry Sauce, if desired. Store cake in refrigerator.
Note: For testing purposes only, we used Pillsbury Ready-to-Bake Chocolate Chip Cookies, Betty Crocker SuperMoist Chocolate Fudge Cake Mix, Betty Crocker Walnut Supreme Brownie Mix, and Betty Crocker Creamy Chocolate Frosting. If you use a different brand of brownie mix, make brownies by the "fudgelike" directions and bake according to times and temperatures for a 9-inch square pan.
Tip: Cake, brownie layer, cookies, and Strawberry Sauce can be made ahead. Assembled cake keeps well for several days and is better if chilled overnight.
*You can use homemade cookies. Just reduce baking time slightly so cookies will be soft. Cookies should be about 2 1/4 inches in diameter.