In advance: Make 1/8 in. thick candy shells in baking cups. You will need 1 mini and 1 standard shell for each treat. Chill until firm, then carefully peel baking cup off candy shell. Level top edge with knife or place on warming plate if necessary.
Prepare cereal treats. Shape into small (2 x 1 1/4 in. high) and large (3 1/4 x 1 in. high) mounds for icing tops. Cover with melted white candy. Attach cherry sour to top of small mound and mini candy cup to top of large mound. Let set. Using melted candy in cut parchment bag, pipe swirls; let set. Fill cups with chocolates and stack.