1 (9 inch) prepared chocolate cake mix
1 (8 ounce) container frozen whipped topping, thawed
1/4 cup white sugar
1 (16 ounce) package frozen whipped topping, thawed
1 (12 ounce) container sweetened condensed milk
1/2 cup white sugar
5 tablespoons cornstarch
1/2 teaspoon salt
Prepare and bake cake mix according to package directions for a 9x13 inch pan. Bake as directed on the package. Cool.
In a large bowl, beat together the white sugar, 1/2 cup white sugar and the cornstarch. Beat in the salt and 1/2 teaspoon of salt until mixture resembles coarse crumbs. Spread the cooled mixture into the bottom of the prepared pan.
Cover with the cooled and spread whipped topping over the cake. Let cool for 10 minutes before removing from pan. Cool completely in pan on wire rack.