Tres Leches Cake

I made this cake for my son's high school graduation. It makes a large cake, enough for 15-20 people.

The Cake:
5 eggs
1 tsp baking powder
1 c sugar
1/2 tsp vanilla extract
1 - 1/2 c all purpose flour
1/2 c unsalted butter

2 c whole milk
1 (14 oz) can sweetened condensed milk
1 (12 oz) can evaporated milk
1 - 1/2 c heavy whipping cream
1 tsp vanilla extract

Preheat oven to 350 degrees. Grease and flour a 9 x 13 inch pan.
Sift flour and baking powder together.
Cream butter and 1 cup of the sugar, add eggs and 1/2 tsp vanilla.
Add the flour mixture to the butter mixture, adding flour 2 T at a time.
Bake at 350 degrees for 30 minutes.
Combine the whole milk, condensed milk, evaporated milk, together and pour over the top of the cooled cake.
Whip the heavy cream, 1 tsp vanilla, and 1 c of sugar until stiff peaks form with the electric mixer.
Spread whipped cream on cake and refrigerate.

Cheater's method:
Use 2 boxes of white cake mix instead of making the cake from scratch.