Preheat oven to 350F. Grease a 9x13 metal baking pan with nonstick cooking spray.
In a large bowl, whisk together flour, cornstarch, baking powder, and salt.
1 cup all purpose flour, 1/4 cup cornstarch, 1 ½ teaspoons baking powder, 1/4 teaspoon kosher salt
In the bowl of your stand mixer, beat the egg yolks and sugar until pale yellow.
5 large eggs, 1 cup granulated sugar
Add vanilla and milk. Beat until well combined.
1 teaspoon vanilla extract, 1/3 cup whole milk
Transfer the yolk mixture to the bowl with the flour mixture. Fold with a rubber spatula until well combined. Set aside.
Clean and dry the bowl of your stand mixer well.
To the bowl of your stand mixer, add egg whites. Beat until stiff peaks form.
Carefully transfer the egg whites to the bowl with the rest of the batter. Fold with a rubber spatula until combined. Be careful not to deflate the egg whites.
Pour cake batter into the prepared baking pan.
Bake for 20-25 minutes, or until a toothpick inserted in the center comes out clean.
Remove cake from the oven and let cool completely.
Once the cake has cooled, use a fork to poke holes across the top.
In a medium bowl, whisk together sweetened condensed milk, evaporated milk, and whole milk.
14 ounce can sweetened condensed milk, 12 ounce can evaporated milk, 1/2 cup whole milk
Pour the milk mixture over the top of the cake, covering all of it.
Refrigerate for at least 2 hours, or overnight, until all the milk has soaked into the cake.
When ready to serve, add heavy cream, vanilla, and powdered sugar to the bowl of your stand mixer.
1 ½ cups heavy cream, 1/2 teaspoon vanilla extract, 1/4 cup powdered sugar
Beat with the whisk attachment until soft peaks form.
Spread whipped cream in an even layer on top of the cake.
Lightly add a dusting of cinnamon over top.
Serve garnished with sliced strawberries or maraschino cherries.
Notes
Kosher salt: Sea salt is a good substitute. If you use table salt, use half the amount.
Whole milk: I recommend using whole milk for the richest, moistest cake and topping.
Sweetened condensed milk: I recommend using full-fat milk for the richest topping.
Evaporated milk: I also recommend using full-fat evaporated milk for the topping.