With a stand or handheld mixer, whisk the two egg whites on high speed in a bowl for about 2-3 minutes, or until soft peaks form. Set aside.
Preheat the oven to 350 degrees F and line a standard 12 slot muffin tin with liners.
Sift together flour, cornstarch, salt, and baking powder. Set aside.
In a large bowl, cream together the butter, sugar, and strawberry jell-o powder until light and fluffy, about 2-3 minutes.
Beat in egg yolks until just combined.
Stir in milk, vanilla, and strawberry puree.
Stir in dry ingredients until just mixed. Don’t overmix.
Using a spatula, gently fold the whipped egg whites into the cake batter.
Divide the batter evenly between the prepared muffin slots (I used a cookie scoop).
Bake for about 10-17 minutes in the preheated oven, or until a tooth pick inserted into the center of the cupcakes come out clean.
Remove from oven and place the cupcakes onto a wire rack to cool completely.