Mix the sugar, salt, and flour in a bowl.

Cut the butter into cubes, then add to the flour mixture.

Add the cold milk to the mixture and mix the dough until fully incorporated.

Roll out the dough and transfer it into a pie dish.

Combine the evaporated milk, condensed milk, eggs, and vanilla extract in another bowl.

Whisk the egg whites in a separate bowl until fluffy.

Slowly fold in the fluffy egg whites into the pie filling.

Pour the pie filling into the pie dish.

Bake in a 350 F or 175 C oven for 40 to 45 minutes.