How to Make It
Preheat oven to 350°F. Beat sugar and butter with a heavy-duty electric stand mixer on medium speed until light and fluffy, 3 to 5 minutes. Add egg whites in thirds, beating well after each addition.
Sift together cake flour, baking powder, and salt. Add flour mixture and water alternately to sugar mixture, beating on low speed just until blended after each addition. Stir in vanilla. Gently fold in chopped flower petals. Divide batter evenly among 4 greased (with shortening) and floured 8-inch round cake pans.
Bake in preheated oven until a wooden pick inserted in center comes out clean, 18 to 22 minutes. Cool cakes in pans on wire racks 10 minutes. Transfer cakes from pans to wire racks, and cool completely, about 30 minutes.
Spread Strawberry Cream Frosting between cake layers and on top and sides of cake. Garnish with fresh edible flowers.