In a medium bowl, heat white pieces in the microwave at 50% power for 1 minute, stirring every 15 seconds, or until melted. Stir in peppermint extract and 1/4 teaspoon oil. Add additional oil in 1/8 to 1/4 teaspoon increments to reach desired dipping consistency.
Place a grid cooling rack on top of a piece of waxed paper. Using scissors, cut large marshmallows in half crosswise. Place one marshmallow half on a fork and dip into melted chocolate mixture. Allow excess to drip off; place onto cooling rack, removing from fork. Repeat with remaining marshmallow halves.
Thread tiny marshmallows one-third of the way down on a toothpick. Dip marshmallows into melted mixture (reheat in microwave if chocolate begins to set in bowl.) Place dipped marshmallows onto cooling rack, leaving on toothpicks. Working quickly before chocolate sets, decorate with edible glitter or color remaining melted mixture with blue paste color, drizzle over marshmallows, then decorate with glitter.
Insert end of toothpick opposite mini marshmallows into the outside of the large dipped marshmallow, mimicking a snowflake, about 6 toothpicks per marshmallow. Repeat with remaining pieces. Serve as a garnish on the side of a mug of hot chocolate, if desired.