In a large bowl, cream butter and sugar. Add the eggs, orange zest and extract; beat until combined. Combine the flour, salt and baking soda; add to the creamed mixture alternately with sour cream. Spoon into two greased 9-in. heart-shaped baking pans; spread evenly in pans. Bake at 350° for 25-30 minutes or until a toothpick inserted in the center comes out clean. Cool for 10 minutes before removing from pans to wire racks to cool completely.
Cut 1-1/2 in. off the pointed ends of each heart cake; set aside. Place the large pieces on a 17x15-in. covered board, placing cut sides of hearts together, forming wings. Trim the reserved pointed end pieces to form the top and bottom of the butterfly’s body.
In a small bowl, cream butter and cream cheese. Add confectioners' sugar and vanilla. Remove 1/2 cup frosting and tint yellow; set aside. Frost cake sides and top with white frosting. Cut a small hole in the corner of a pastry or plastic bag; insert #6 round tip. Fill bag with remaining white frosting; set aside.
Frost a portion of each wing with yellow frosting. Decorate butterfly's body and wings with colored sugars. Pipe white frosting to separate colored sections on wings and to outline the body. Decorate the wings with gumdrops.
Using a citrus stripper, cut two 12-in.-long pieces of orange peel. Wrap around the handle of a wooden spoon. Remove from spoon and place above the body for antennae.