Preheat oven to 350 and grease a 9x13 pan.
Make cake batter according to the boxed mix package directions, with 2 exceptions: use 1 extra egg and replace the oil with melted butter.
Bake the cake according for 30-40 minutes or until a toothpick inserted into the center of the cake comes out clean.
Allow the cake to cool for 10 minutes, then poke holes in the cake with the handle of a wooden spoon.
Whisk together evaporated milk, sweetened condensed milk, and 1 cup of heavy cream. Pour the milk mixture over the cake.
Allow the cake to cool for at least 30 more minutes so the cake reaches room temperature.
Refrigerate for at least 6 hours.
Whip together remaining heavy cream, sugar and vanilla until soft peaks form. Frost the cake with this whipped cream.
Serve and enjoy!
