Preheat oven to 350ºF (176ºC).
Grease a 9-by-13-inch baking dish.
In a large bowl, add eggs, 3/4 cup sugar, and vanilla. Use an electric mixer and mix on high for about 3 minutes. It will become pale and thick.
Add in the melted butter and flour. And before mixing, directly on top of the flour, add the baking powder and salt. With a spoon, mix the dry ingredients together first just to disperse the salt and baking powder into the flour. Don’t over-mix. Pour batter into baking dish and bake until a fork inserted in center comes out clean, approximately 25 minutes (if using a metal baking dish it may be done much sooner).
While the cake is in the oven take a medium bowl and whisk together the sweetened condensed milk, evaporated milk, and the whole milk.
Right when the cake comes out of the oven, poke the top of it many times with a fork and then pour half of the milk mixture over the whole cake. The milk will become absorbed. Then go ahead and slowly pour more milk until the cake doesn't absorb anymore. This may be the whole mixture or a little less but make sure to wait and see if the milk gets absorbed before pouring more over the cake.
Allow cake to cool before topping with whipped cream.
While cake is cooling, prepare whipped cream by pouring heavy cream into a medium/large bowl. Add in 1/4 cup sugar. Mix with an electric mixer until you start forming stiff peaks. Spread whipped cream over the top of the cake, cut yourself a piece, and enjoy!