Pour 2 cups of milk into a medium-sized saucepan.
Warm the milk over medium heat, stirring occasionally.
Add 1 cup of white chocolate chips to the warmed milk.
Stir constantly until the white chocolate chips are fully melted and the mixture is smooth.
Stir in 1 teaspoon of vanilla extract.
Divide the hot chocolate into three separate bowls or mugs.
Add a few drops of blue food coloring to one bowl, green to another, and purple to the last.
Stir each bowl until the color is evenly mixed.
Carefully pour each colored hot chocolate into a serving mug, layering or marbling as desired.
Top with whipped cream.
Decorate with sprinkles, edible glitter, or candy decorations.
Add a candy tail or marshmallows if desired.
Serve immediately and enjoy your mermaid hot chocolate.