Preheat your oven to 350°F (175°C) and line a 12-count cupcake pan with liners. Set aside.
In a large mixing bowl, add ¾ cup unsalted butter, ⅔ cup granulated sugar, and ⅓ cup light brown sugar. Beat on high speed until whipped and yellow. Scrape down the sides of the bowl.
Add 1 cup of 2% or whole milk and 1 ½ teaspoons vanilla extract. Beat to combine. Scrape down the sides of the bowl; set aside.
In a separate medium bowl, whisk together 1 cup all-purpose flour, 1 teaspoon baking powder, ½ teaspoon salt, and ¼ teaspoon baking soda. Add this dry mixture to the wet mixture, and beat to incorporate but don't overmix; set aside.
In a separate large bowl, add the 3 large egg whites and beat on high speed until stiff peaks form, but aren’t dry. Make sure that no yolks are in the whites.
Gently fold in the egg whites into the cupcake batter using a large rubber spatula. Do not stir aggressively; gently fold over the batter until the whites have folded in.
Fill each cupcake liner 3/4-full with batter and bake for about 20 minutes, or until a toothpick inserted in the center comes out clean or with a few moist crumbs. Rotate the pan midway through baking.
Poke the cupcakes with a toothpick after they come out of the oven, going down about halfway, and poking them in 10 spots each; set aside.
In a large measuring cup, combine ½ cup evaporated milk, ½ cup sweetened condensed milk, and ½ cup heavy cream. Stir until well combined.
Gently pour the milk mixture over the cupcakes, allowing time for it to soak in. Go back and repeat as necessary until all the milk has been used.
To prepare the frosting, beat 1 ½ cups unsalted butter until light and fluffy. Add 6 cups confectioners’ sugar, 1 teaspoon vanilla extract, ½ teaspoon salt, and drizzle in 3 tablespoons heavy cream. Beat until the frosting is light and fluffy.
Once the cupcakes have cooled, spoon or pipe the frosting onto each cupcake. Optionally garnish with strawberries or other berries before serving.
