Decadent Chocolate Raspberry Cake

Ingredients

• 1 3/4 cups all-purpose flour
• 3/4 cup dark unsweetened cocoa powder
• 1 teaspoon baking powder
• 2 teaspoons baking soda
• 2 cups granulated sugar
• 1 teaspoon salt
• 1 cup buttermilk
• 1/2 cup vegetable oil
• 2 eggs, room temperature
• 2 teaspoons vanilla extract
• 3/4 cup water, boiling
• 12 ounces frozen raspberries, thawed
• 1 1/2 tablespoons cornstarch
• 1/3 cup granulated sugar
• 2 tablespoons lemon juice
• 1 2/3 cups heavy cream
• 12 ounces bittersweet chocolate, chopped
• 1 tablespoon corn syrup
• 6 ounces mascarpone
• 1 1/4 cups heavy cream
• 1/2 cup plus 1 tablespoon confectioners' sugar
• 3/4 teaspoon vanilla
• 2-3 (6-ounce) containers fresh raspberries, for garnish