Red, White, and Blue Ice Cream Cake: Recipes + Menus : gourmet.com

Ingredients

• 1 1/2 cups all-purpose flour plus more for dusting
• 1/2 teaspoon baking powder
• 1/4 teaspoon baking soda
• 1/4 teaspoon salt
• 1 stick (1/2 cup) unsalted butter, softened
• 1 cup sugar
• 2 large eggs, warmed in their shells in warm water for 5 minutes
• 1 teaspoon pure vanilla extract
• 1/2 cup sour cream
• 12 ounces (2 1/4 cups) fresh blueberries
• 1/3 cup sugar
• 2 tablespoons light corn syrup
• 1 teaspoon fresh lemon juice
• 1 teaspoon water
• 1 teaspoon cornstarch
• 12 ounces (3 cups) fresh raspberries
• 1 1/2 teaspoons cornstarch
• 1 1/2 quarts vanilla ice cream
• 1 1/2 cups chilled heavy cream
• 1/3 cup confectioners' sugar
• 1 cup mixed fresh blueberries and raspberries
• A 9-inch springform pan; a small offset metal spatula