In large saucepan melt butter over low heat. Add marshmallows and stir until completely melted. Remove from heat.
Add Kellogg’s Rice Krispies cereal. Stir until well coated.
Using a large spoon coated with cooking spray divide warm cereal mixture into portions.
Using buttered hands shape each portion into 2 1/2- x 1 1/2-inch egg shapes. (Or, coat insides of plastic snap-apart Easter eggs with cooking spray.)
Press cereal mixture into eggs. Remove cereal mixture from plastic eggs. Cool.
Heat chocolate over low heat until melted, stirring constantly. Dip bottoms of cereal eggs into chocolate.
Decorate with sprinkles. Place on wax-paper-lined baking sheet. Refrigerate until chocolate is firm.