Make mini cupcakes. Bake cupcakes in baking cups; cool completely. Prepare buttercream icing. Use spatula to ice cupcake tops smooth. Sprinkle with sparkling sugar. Attach penguin icing decoration.
Make cookies. You will need one of each shape for each treat. Prepare dough and roll out to 3/16 in. thick. Cut one circle using second smallest (3 1/4 in.) cutter and one circle using the largest cutter from set for each treat.
Invert ball pan and spray with vegetable pan spray. Drape smaller circle over every other pan cavity, pressing to smooth surface. Bake 10-14 minutes, or until firm and golden brown. Cool pan on cooling grid 10 minutes. Carefully loosen bottom edges of treat using spatula.
Place larger circles flat on ungreased cookie sheet. Bake 11-14 minutes or until golden brown. Cool on sheet 2 minutes; remove to cooling grid to cool completely.
Cover cookies and marshmallows with melted candy. Melt white Candy Melts candy according to package directions. Cut marshmallows in half.
Position cookies and marshmallows on cooling grid placed over waxed paper. Pour melted candy over both. Chill until firm.
Decorate igloo. Use melted white candy and a cut parchment bag to pipe brick lines on shaped cookie and to attach cut marshmallow for door. Chill until firm.
Make piñata treats. Place mini cupcake on treat base; cover with igloo cookie. Use melted white candy and a cut parchment bag to pipe a line around cookies to seal. Chill until firm.