To make the cake: Preheat your oven to 350°F and spray or butter a 9x13” baking pan.
Combine the flour, baking powder, and salt in a large mixing bowl.
Using two separate bowls, separate the eggs: egg whites in one bowl, egg yolks in the other.
Add the ¾ cup of sugar to the egg yolk bowl. With a hand mixer, beat on high speed until yolks are pale yellow. Then, add the ⅓ cup whole milk and 1 teaspoon vanilla, and stir to combine.
Pour your egg yolk mixture over the flour mixture in the other bowl and stir gently with a spatula until just combined.
With the same hand mixer, or in the bowl of a stand mixer with the whisk attachment, beat the egg whites on high speed until soft peaks form. This will take anywhere from 3 to 10 minutes.
With the mixer on medium-low, pour in remaining ¼ cup sugar and beat on high speed until egg whites are stiff. This will take anywhere from 5 to 15 minutes. You’re looking for thick, glossy whites.
Gently fold the whipped egg whites into the batter with a spatula. Pour batter into your prepared pan, spreading gently to even out the surface.
Bake for 25-35 minutes, or until a toothpick in the center comes out clean. Remove from the oven and allow the cake to cool completely.
To make the milk mixture: While the cake is baking, combine the evaporated milk, sweetened condensed milk, and whole milk in a large measuring cup or pourable jug. Let sit until the cake has cooled.
Slowly pour the milk mixture over the top of the cake, making sure to pour the milk mixture near the edges and all around.
Place the cake in the refrigerator and chill for at least 1 hour or overnight, to allow the milk to soak in.
To make the topping: The next day, whip the heavy cream, sugar, and vanilla until stiff peaks form.
Spread the whipped topping evenly over the top of the cake. Garnish with ground cinnamon and fresh strawberries, if desired.