For the cake: Arrange an oven rack in the center of the oven. Preheat the oven to 350 degrees F. Butter and flour the bottom and sides of 2 nonstick, 8-inch round, baking pans. Set aside.
In the bowl of a stand mixer, fitted with a whisk attachment, combine the cake mix and orange zest. Mix for 20 seconds at low speed until the zest is incorporated. Add the orange juice, egg whites, and vegetable oil. Blend at low speed for 30 seconds. Increase the speed to medium and beat for 2 minutes, scraping the bottom and sides of the bowl with a spatula, as needed. Divide the batter between the prepared pans and bake until golden and a cake tester inserted into the center of the cakes comes out clean, about 30 to 32 minutes. Remove from the oven and cool the pans on a wire rack for 15 minutes. Turn the cakes out onto a wire rack and allow to cool completely, about 1 hour.
For the frosting: In the bowl of a stand mixer, fitted with a paddle attachment, beat together the butter and creme fraiche at high speed until smooth, about 10 seconds. With the machine running at medium-low speed, gradually add the powdered sugar until incorporated. Add the raspberry jam and increase the speed to high. Beat until the frosting is smooth and spreadable, adding water, 1 teaspoon at a time, if needed.
To assemble the cake: Arrange 1 cake layer, flat side up, on a cake stand. Using a spatula, spread a thin layer of frosting on top leaving a 1/2-inch border. Spread 1/4 cup of raspberry jam on top of the frosting. Arrange the other cake layer on top. Using a spatula, frost the top and sides of the cake. Decorate with fresh raspberries. Cut the cake into wedges with a slightly wet knife and serve.
Store the cake in a plastic container in the refrigerator. Allow the refrigerated cake to stand at room temperature for 30 minutes before serving.
Recipe courtesy of Giada De Laurentiis