Grease and flour 3 9” round cake pans; set aside. Preheat oven to 325°F.

In a medium bowl, sift together the cake flour, baking powder and salt; set aside.

In a separate bowl, whisk together the milk, sour cream and vanilla extract; set aside.

Using a countertop mixer fitted with the paddle attachment, cream together the butter and sugar until light and fluffy (~3-4 minutes on medium-high speed).

Add about half of the flour mixture to the bowl; mix on low speed until well combined.

Add the milk mixture to the bowl. Mix on low until well combined.

Add the remaining flour mixture; mix on low until well combined. (Tip: Don’t forget to scrape down the sides of the bowl to ensure all ingredients are fully mixed.)

In a separate bowl, beat egg whites on medium speed until stiff peaks form. Carefully fold the egg whites into the cake batter until fully mixed.

Divide the batter evenly between the 3 cake pans. Bake at 325°F for 34-36 minutes, or until a toothpick inserted into the center of the cake comes out clean.

Wash berries and place in a medium saucepot over low heat. Once the berries are warm, muddle them in the saucepot until no large pieces remain.

Cook blackberry puree for 3-4 minutes over low heat (or until ~1 cup remains), stirring often to prevent burning. Remove puree from heat and let cool completely.

Optional: Use a food mill to deseed the mixture.

Meanwhile, in the bowl of a countertop mixer fitted with the paddle attachment, beat the softened cream cheese, powdered sugar, vanilla extract and almond extract on high speed until smooth.

With the mixer running, slowly pour in the heavy cream. Stop and scrape the sides of the bowl once or twice during this step. Continue beating until frosting has thickened to a spreadable consistency and will hold medium peaks (~4-5 minutes on medium-high speed).

Add the cooled blackberry puree and mix on low speed until well combined.

Place one layer of cake on a large plate. Frost the top of the layer with Blackberry Frosting. Repeat with the remaining layers of cake.

Using an offset spatula, frost the sides of the cake. (Note: It is helpful to refrigerate the frosting for about 20-30 minutes before frosting the sides of the cake.)

Garnish the top of the cake with fresh blackberries before serving.