In a slow cooker, add 2 cups of heavy cream, 2 cups of whole milk, and 1 cup of white chocolate chips. Pour in 1 cup of sweetened condensed milk and 2 teaspoons of vanilla extract. Stir gently with a whisk until well-blended.

Cover the slow cooker and set it to low heat. Allow to cook for 2 to 3 hours, stirring gently every 20 minutes.

Once melted and combined, add 1-2 drops of green food coloring and a tiny bit of yellow food coloring, mixing well until the desired color is achieved.

Ladle the hot chocolate into mugs and allow guests to customize their drinks with whipped cream, marshmallows, and crushed candy canes.