Make cake: Preheat oven to 350F. Mist a 13-by-9-inch baking pan with cooking spray. In a bowl, combine flour, baking powder and salt.
In a bowl, using an electric mixer on medium-high speed, beat butter and sugar until light, about 3 minutes.
Add yolks, one at a time, beating after each. Beat in vanilla.
Add flour mixture in three parts to form a stiff batter.
Using clean beaters and bowl, beat egg whites until peaks form. Stir 1/3 of whites into batter; fold in remaining whites.
Spread batter in pan.
Bake until a toothpick inserted into center comes out clean, about 30 minutes. Use a fork to poke holes on top of cake. Cool to room temperature on a rack.
Whisk together whole, condensed and evaporated milks.
Pour over cake, cover and chill for at least 4 hours.
To serve, whip cream with sugar and vanilla until firm peaks form.