Mascarpone-Filled Cake With Sherried Berries

Name: Mascarpone-Filled Cake With Sherried Berries
Cuisine: European
Ingredients: 2 cups sifted cake flour (not self-rising; sift before measuring); 1 teaspoon baking powder; 1 teaspoon baking soda; 1/2 teaspoon salt; 1 stick unsalted butter, softened; 1 cup sugar; 1 teaspoon pure vanilla extract; 2 large eggs; 1 cup well-shaken buttermilk; 1/2 cup Fino (dry) Sherry; 1/2 cup sugar; 4 cups mixed berries, cut if large; 8 ounces mascarpone (1 cup); 1 cup chilled heavy cream; 1/4 cup sugar; confectioners sugar