Preheat the oven to 350 degrees Fahrenheit and line a cupcake pan with cupcake liners.
Quarter the strawberries and puree until smooth. Measure 1/3 puree and set aside any extra to use for frosting.
Mix the 1/3 cup strawberry puree, milk and vanilla.
In a medium bowl whisk together the flour, baking powder, and salt. Set aside.
In a large bowl cream the butter until light and fluffy. Continue to mix while slowly adding the sugar.
Mix in the egg until just barely incorporated, then add the egg whites 1 at a time until just mixed in.
In a few alternating parts, starting and ending with the flour mixture, mix in the flour mixture and strawberry mixture.
Spoon the batter into the cupcake pans and bake 20 - 25 minutes, rotating the pans 180 degrees during baking. The cupcakes are done when a toothpick comes out clean after inserting into the middle of the cupcake.
Cool 5-10 minutes in the pan then cool completely on a wire rack. Once completely cool to the touch frost the cupcakes with the fresh strawberry frosting.