Preheat the oven to 350°F and generously spray three 8- or 9-inch round cake pans (or you can use one at a time) with cooking spray. Using a stand mixer fitted with the paddle attachment (or a large mixing bowl with a hand mixer), combine the butter, sugar, egg whites and strawberry extract and beat on medium speed until creamy and free of lumps.
In a separate bowl, combine the flour, baking powder and salt. Mix well. Gradually add to the butter mixture and beat on medium speed until just combined. Add the buttermilk and mix until combined. Fold in the strawberries. Divide the batter between three same-size bowls. Add approximately 1/4 teaspoon of red food coloring to one bowl and mix until color is even throughout. Add approximately 1/2 teaspoon of the food coloring to another bowl and stir until color is even.
Pour the contents of each bowl into a prepared cake pan and bake one at a time in the preheated oven for 25-30 minutes, or until a toothpick inserted into the centers come out clean. Let cool in pan for 5 minutes, remove from pan and let cool completely on a wire rack. Using a serrated bread knife, cut the rounded tops off each cooled cake.
PREPARE THE FROSTING
Place the freeze-dried strawberries in a ziploc bag and turn into a fine powder by pounding with a heavy spoon or rolling pin. In a large bowl, mix (using whisk attachments) the powdered strawberries, butter, confectioner’s sugar and milk with a hand-held or stand mixer on medium speed until combined. Add the whipped topping and mix on medium speed for 3 minutes. Refrigerate until cake is ready to frost.
ASSEMBLE THE CAKE
Place the darkest red cake in the center of a cake or serving plate. Spread the frosting evenly and generously over the top in an even layer. Top with approximately 1/4 cup of the strawberry ice cream topping and spread in an even layer, leaving a 1-inch margin around edge. Top with the pink cake and repeat with a layer of frosting and ice cream topping. Top with the white cake.
Using an offset or icing spatula, apply the remaining frosting to the top and sides of the cake. Top with strawberry slices and refrigerate until ready to serve.