Spray 13x9-inch pan with cooking spray. In 3-quart saucepan, melt butter over medium-low heat. Add marshmallows; cook, stirring frequently, until melted and mixture is smooth. Remove from heat.
Stir in both cereals and the raisins until coated well. Pour mixture into pan. With sprayed rubber spatula, spread evenly in pan, pressing lightly.
With handle of wooden spoon, make 36 deep indentations in 6 rows of 6 on top of bars. Place 1 candy, deep into each indentation, pressing slightly. Cool completely, about 1 hour.
Cut into bars with 1 candy in center of each.