In a large microwave-safe bowl, combine the green candy melts and heat them in your microwave on high for 1 minute. Stir and continue microwaving in 15-second intervals until smooth.

Once the melts are smooth, stir in the sweetened condensed milk and the Creme de Menthe until fully blended together.

Cover the mixture and let it cool at room temperature for about 10-15 minutes, stirring every 5 minutes until it thickens.

Prepare a piping bag fitted with a large star tip and pipe tree shapes onto a parchment-lined baking sheet.

Press a gold star sprinkle at the top of each tree and sprinkle the rainbow nonpareils over the fudge while still soft.