Preheat the oven to 350 degrees F. Liberally grease a 13x9" baking pan with cooking spray and set aside.

In a large bowl, prepare the cake mix according to package directions. Pour into the prepared pan and bake for about 20-22 minutes or until a toothpick inserted near the center comes out clean or with moist, not wet, crumbs. Cool for about 5-10 minutes.

Once cooled for a little bit, poke holes over the entire cake using the handle of a wooden spoon or spatula. Meanwhile, in a medium bowl, whisk together the sweetened condensed milk, evaporated milk, 3/4 cup of the heavy cream and the vanilla together until blended. Pour the mixture over the cake, allowing the mixture to fill the holes in the cake. The mixture may pool around the edges of the cake; this is okay. Refrigerate the cake for 6 hours or overnight.

Once cake has set in the fridge, make your whipped cream. In the bowl of a stand mixer, beat the remaining 1 cup heavy cream and the Tablespoon of sugar together on high speed for about 3 minutes or until it has semi-stiff peaks. Grate in half of a disc of the Abuelita chocolate (or about 1 oz of any other type of good quality chocolate, such as Baker's, Ghirardelli, etc). Continue beating until stiff peaks form.

Spread the whipped cream over the cake in an even layer. Garnish each slice with chocolate shavings/curls, or sprinkles. Store airtight in the fridge.