Good-Cooking - Red Velvet Pudding Cake

Ingredients

• 1 (12 ounces) package whole frozen raspberries (not in syrup)
• 1 (18.25 ounce) box devil's food cake mix plus the specified amount of cooking oil and eggs to make cake
• 2 cups water
• 1 (6 ounce) package raspberry gelatin
• 1 tablespoon cornstarch
• 2 ounces semisweet chocolate
• Confectioners' sugar
• 1 (16 ounce) container frozen whipped topping (optional)