Melt butter in a large pot, add marshmallows and stir until completely melted. Remove from heat.
Gently stir in Cocoa PEBBLES™ until completely coated. Evenly flatten mixture into lightly greased 9″ x 13″ pan. Cool completely.
Cut a 1-2″ strip the width of the pan and divide into 32 pieces and roll into small balls. Cut the remaining pan of bars into 4 by 4 rows.
Melt the candy melts as directed on package. Carefully dip small balls in desired color of melts until fully coated. Set on wax paper and place an eye candy on each ball. Cool completely. Dip PEBBLES™ rectangles into melted candy coating until about 2/3 of bar is submerged. Softly tap on edge to remove excess. Bars may be delicate, so use a fork to support the bar. Line a cookie sheet with waxed paper, place bar and sprinkle with sprinkles. Cool completely.
Use toothpicks to attach “eyes” to squares. Use decorative sticks on bars for handles. Boo!