Heat oven to 350 degrees. Spray 9X13 baking dish or pan with cooking oil or baking spray.
In a bowl add the devil's food cake mix, three eggs, 11/4 cups milk and 1/4 cup cocoa. Whisk until combined.
Pour cake batter into cake pan and bake 30-35 minutes depending on oven and pan type. Check with toothpick.
When the cake is done set aside to cool for 30 minutes and start the next steps.
Tres Leches Filling – In a bowl mix 1 can of sweetened condensed milk, 1 can of evaporated milk, 1 cup of whole milk and 1/4 cup of cocoa powder. Whisk until combined and set aside.
Frosting – In a separate bowl add 1/2 cup of sugar, 1/4 cup of cocoa powder and two cups of heavy whipping cream. Whip until soft peaks appear and refrigerate.
Once cake has cooled for thirty minutes, using a fork, punch holes in the cake uniformly on the top.
Pour the Tres Leches Filling slowly over the top of the cake until totally absorbed. Place in refrigerator for at least two hours before frosting.