Blackberry Cake With Cream Cheese Frosting Recipe

Name: Blackberry Cake With Cream Cheese Frosting Recipe
Prep time: 20 min
Cook time: 30 min
Total time: 50 min
Yield: 8
Ingredients: 7 ounces fresh blackberries (about 1 1/4 cups; 200g), firm and tart (see note); 4 ounces unsalted butter (about 8 tablespoons; 110g), softened to about 60°F (16°C); 5 1/4 ounces sugar (about 3/4 cup; 145g); 1 1/4 teaspoons baking powder, preferably not aluminum free (see note); 1/4 teaspoon baking soda; 1/4 teaspoon (1g) Diamond Crystal kosher salt; for table salt, use about half as much by volume or the same weight; 1/8 teaspoon ground cinnamon; 2 ounces egg whites (about 1/4 cup; 55g), brought to about 70°F (21°C); 5 1/2 ounces bleached cake flour (about 1 1/4 cups, spooned; 155g), such as Swans Down, sifted (see note); To Serve:; 1 batch Cream Cheese Frosting; Additional blackberries, to garnish