Pre heat over to 350 degrees. Spray thre 8 inch cake pans w/ Pam (w/ flour) set aside.
Combine flour, sugar, baking powder, baking soda and salt. Add Buttermilk, butter and vanilla. Beat w/ a mixer on low speed for 30 seconds. Beat on medium to high speed for 2 minutes, scraping bowl. Add egg whites and beat for 2 minutes more.
Pour into prepared pans. Bake for 30 to 35 mins or until toothpick inserted comes out clean. Cool for 10 minutes. Remove the cakes from the pans and allow them to cool completely on wire racks while preparing the filling and icing.
Add granulated sugar to diced strawberries and set aside. Soften gelatin in cold water, then add boiling water. Stir until dissolved. Stir into strawberry mixture and allow it to cool. With a mixer, cream mascarpone and powdered sugar. Gently combine strawberries and cheese mixture. Whip cream until stiff, and gently fold into strawberries. STore in refirgerator until ready to use.
With electric mixer, blend cream cheese and butter until fluffy and smooth. Add vanilla and mix well. Beat in powdered sugar 1 cup at a time until combined.
Place one layer of cake on a plate. Cover layer w/ half of strawberry mixture. Place second layer over the top. Cover second layer w/ remaining strawberry mixture, and top with the third layer. Frost cake w/ prepared icing and decorate as desired.