Line 2 ( 9-inch) square cake pans with aluminum foil. Spray with no- stick spray. Spray rubber spatula with no-stick spray; set aside.
Put marshmallows and Spread in large microwave-safe bowl and microwave uncovered at HIGH 3 minutes, stirring once, until marshmallows are melted. Stir in rice cereal until coated. Press mixture evenly into prepared pans with greased spatula. Freeze 15 minutes.
Press Breyers® Homemade Vanilla Ice Cream evenly over rice cereal layer in one of the pans. Remove layer from other pan and invert on top of Ice Cream. Wrap in aluminum foil and freeze 2 hours.
Remove from foil and cut into 12 bars. Roll edges in sprinkles and freeze until ready to serve.