Mascarpone-filled cake with sherried berries (visit site)

Ingredients

For the cake:

• 2 cups sifted cake flour (not self-rising), like Swan's Down
• 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

For the berries:

• 1/2 cup Fino (dry) Sherry
• 1/2 cup sugar
• 4 cups mixed berries, cut if large

For the cream:

• 8 ounces mascarpone (1 cup)
• 1 cup chilled heavy cream
• 1/4 cup sugar