Preheat oven to 350
Crack the eggs and separate the whites from the yolks. Place the whites in the fridge for later.
In the bowl with the yolks, add the sugar and beat with hand mixer until smooth
Add flour, baking powder, vanilla and milk. Mix with hand mixer until mixed.
Remove the whites from the refrigerator. Add salt and beat them with the hand mixer on high for 2-3 minutes until soft peaks form.
With a rubber spatula, GENTLY fold egg whites into the cake batter.
Grease the bottom of an 8x8 or equivalent baking dish (I used an 8x11 rectangle dish) with the butter
Pour cake batter in dish and bake at 350 for 50 minutes until a toothpick inserted comes out clean.
Let cake cool for 10-20 minutes
While cake is cooling - in a bowl, mix together the "tres leches"
Poke holes with a straw or make small slits with a knife throughout the cake
If serving right away, pour 1/2 the milk mixture over the holes in the cake and let rest for 30-60 minutes. When serving, cut a piece of cake and serve with a moat of the remaining milk around the cake on the plate.
If serving later that day or next day, pour 1/3 of milk mixture over the cake. Cover and refrigerate. Refrigerate remaining milk mixture separately in an air tight covered bowl. When ready to serve, remove from the fridge, slice pieces and serve by pouring more of the milk mixture over each piece.
Top with a caramel drizzle and sliced strawberries