Tender and fluffy vanilla cake layers with a whipped cream filling, fresh strawberries and strawberry buttercream.
Preheat your oven to 325 degrees F. Spray three 8-inch or four 6-inch round cake pans with non-stick spray and then line with parchment. Spray again. Set aside.
In a medium sized mixing bowl, whisk together the cake flour, baking powder and salt. Set aside.
In the bowl of an electric mixer, fitted with the paddle attachment, cream the butter and the sugar for two minutes on medium-high speed.
Scrape down the sides of the bowl and begin to add the egg whites on medium speed, scraping down the sides and bottom of the bowl between addition. Once all of the egg whites are added, mix for about 1 to 2 minutes on medium speed.
Add the sour cream and vanilla extract and beat until incorporated, about one minute.
With the mixer on low speed, add 1/3 of the flour mixture, followed by 1/2 cup of the buttermilk. Repeat the additions, 1/3 cup flour mixture, 1/2 cup buttermilk and the final 1/3 cup flour mixture. Only mix until the flour mixture is incorporated, about 30 seconds. Scrape down the sides and bottom of the bowl and mix again for another 20 to 30 seconds on low.
Pour about 18 ounces of cake batter into each of the three 8-inch cake pans or 13 ounces in each of the 6-inch pans and bake for 25 to 28 minutes, or until a toothpick inserted into the center of the cake comes out with a few moist crumbs on it. Let cool in the pans for about 15 minutes and then invert onto a wire rack to cool completely. (Tip: spray your wire cooling racks with nonstick spray).
In a small bowl, place the cold water and sprinkle with the gelatin. Let sit for at least 10 minutes. In a small saucepan, bring 1/3 cup heavy cream to a simmer and then stir in the gelatin mixture. Refrigerate, stirring frequently, until cool but not set, about 5-7 minutes.
In a chilled stainless steel bowl with a chilled whisk attachment, beat the remaining whipping cream, icing sugar, and vanilla until it thickens and soft peaks begin to form, about 1 to 2 minutes. Very gradually add the gelatin mixture and continue beating until medium-firm peaks form.
Keep covered and chilled until ready to use.
In the bowl of a stand mixer fitted with a paddle attachment, cream the butter for about 2 minutes. This will soften the butter without it having to be warm.
With the mixer on low speed, gradually add the sifted powdered sugar, one cup at a time, mixing a little in between each addition.
Add the freeze dried strawberries and the strawberry jam.
With mixer on medium speed, add whipping cream and vanilla.
Turn the mixer to medium-high speed and beat for an additional 5 to 7 minutes. The frosting will become lighter in color and texture.
Spread a small dollop of frosting on your cake board. This will act like glue to hold your cake in place.
Place your first cake layer, top side up, on your cake board. Pipe a rim of strawberry buttercream around the edge of the cake.
Spread about 1/2 cup of the whipped cream filling over the cake. Placed diced strawberries on the whipped cream and pat into place with your hand. Spread another 1/2 cup of the whipped cream filling over the strawberries.
Place the next cake layer on top of the filling and repeat steps 2 and 3.
Set your final cake layer, top side down, on your second layer of filling. Apply a thin crumb coat over your entire cake. This does not need to look pretty or be even. This coat of frosting is simply to lock in the crumbs. Freeze your cake for about 10 to 15 minutes to set the crumb coat.
After the crumb coat is set, finish frosting your cake with the strawberry buttercream