Beat butter at medium speed of an electric mixer until creamy; gradually add 1 cup sugar, beating well. Add egg and vanilla, mixing well. Stir in melted morsels.
Combine flour and salt; add to butter mixture, beating well. Shape dough into a flat disc. Cut dough into thirds. Wrap in wax paper. Cover and chill briefly until dough is a good rolling consistency.
Place each portion of dough on a large lightly greased cookie sheet. Cover with wax paper or plastic wrap. Roll dough to 1/4" thickness on cookie sheets. Cut out cookies, using desired cookie cutters. (We tested with 3" and 6" moose cutters.) Sprinkle with sugar. Peel away excess dough.
Bake at 350° for 10 to 11 minutes for small cookies and 12 minutes for larger cookies. Cool 5 minutes on cookie sheets; remove to wire racks, and cool completely.
Place opened can of frosting in microwave. Microwave at MEDIUM (50% power) 45 seconds; stir. Microwave 30 more seconds. Spread frosting over cookie antlers and feet, if desired. Sprinkle with chocolate sprinkles and sparkling sugar, if desired. Let harden on wire racks.