1. Grease a 10 x 15-inch (25 x 38 cm) rimmed baking sheet.
2. Melt the butter in a large saucepan set over low heat. Add the marshmallows; cook, stirring, until melted and well blended. Stir in the vanilla. Add cereal; stir until coated.
3. Firmly press the mixture into an even layer in the prepared pan. Chill until set. Cut out shapes using assorted 1 to 2 1/2-inch (2.5 to 4 cm) flower-shaped cookie cutters.
4. Pipe frosting and attach Jelly-Beans to decorate each treat to resemble flowers.
In keeping with good allergy practices, we remind you to be aware of allergens and to check labels on any packaged goods used. This recipe has been tested using Kellogg's* products. Results with other products may vary.