BEAT sweetened condensed milk, pudding mix and milk in large bowl with electric mixer. Fold in sour cream. Chill 5 minutes.
RESERVE 1/4 cup pudding mixture. In 2 to 2 1/2-quart clear glass bowl, layer half of the pound cake pieces, half of the remaining pudding and half of the raspberries and blueberries. Repeat layers. Spoon reserved pudding mixture on top. Cover; chill at least 2 hours. Top with Star Garnish, if desired, before serving.
HEAT white baking bar in small heavy saucepan over low heat until melted, stirring constantly. Tint with red paste food coloring. Pipe mixture into star shapes on wax-paper-lined baking sheet. Let stand until dry. Carefully peel from wax paper.