Preheat the oven to 350 degrees Fahrenheit; grease 2, 8 or 9 inch round cake pans, or 4, 6-inch round cake pans, dust with flour and tap off excess.
In a medium bowl, whisk together the cake flour (2 ¾ cups), baking powder (1 tbsp.), and salt (¼ tsp). Set aside.
Use a stand mixer with a paddle attachment (or hand held electric beaters) to cream together the room temperature butter (1 cup=2 sticks) and sugar (2 cups) for 5-6 minutes on medium high speed, until pale in color and fluffy.
Add the 6 egg whites one at at time and beat on low speed, followed by the vanilla (1 tsp), vegetable oil (¼ cup), and milk (1 cup) on low speed until combined.
Add the flour mixture to the wet mixture in portions of thirds, and beat on low speed only until just combined- do not over mix.
Turn the mixer off and fold in the pureed strawberries (1 cup). For extra flavor and color punch, fold in an additional ½ cup pulverized, freeze dried strawberry powder at the same time as the pureed strawberries.
Divide the batter equally into the pans and bake at 350 degrees F for 38-43 minutes for 8 inch cake rounds, 35-40 minutes for 9 inch cake rounds, and 18-22 minutes for 6 inch rounds, until top is springy.