To prepare a strawberry cake from scratch, you'll need: 1 cup fresh strawberries, 2 cups sugar, 1 tablespoon vanilla, and 2 tablespoons butter. You can also use frozen strawberries if you prefer. Preheat the oven to 350?F (180?C) and grease and flour two 9-inch cake pans. Set aside. Sift the flour, baking powder, sugar and salt into the bowl of an electric mixer and mix on medium speed until the mixture is light and fluffy, about 2 minutes. Add the butter and vanilla and beat on high speed for 1 minute. Scrape down the sides of the mixing bowl with the back of your mixer to incorporate the dry ingredients. In another bowl, whisk the egg whites until they're stiff peaks. Gradually add the wet ingredients, beating after each addition until just combined. Fold in the strawberry mixture. Spoon the batter evenly onto the prepared pan. Bake the cake for 35 to 40 minutes, or until toothpick inserted in center comes out clean. Allow to cool in pan for 10 minutes before removing from pan and serving.