Heat oven to 350°F. Grease an 8 or 9-inch baking pan with cooking spray.

Cake Batter: Stir together sugar, flour, cocoa, baking powder, baking soda and salt in large bowl. Add sour cream, milk, oil and vanilla; beat on medium speed for 1 minute.

Stir in boiling water (batter will be thin). Pour batter into prepared pan.

Bake for about 15 minutes, or until a toothpick inserted in the center comes out clean. Allow cake to cool completely.

Assemble: Spread a thin layer of fudge sauce over the top of the cake. Remove ice cream from the freezer and allow to sit for 10-15 minutes. Stir well to soften enough to spread onto the cake.

Freeze for several hours, until ice cream is firm.

Frosting: Beat whipped cream for 1 minute. Mix in powdered sugar and vanilla and beat until stiff peaks. Smooth whipped cream over the top and top with sprinkles, maraschino cherry, or other crushed candies for decoration, if desired.

Store ice cream cake in the freezer, covered well, without whipped cream topping for 2-3 months or for 1 week with whipped cream topping.