Melt butter in a large saucepan over low heat. Add marshmallows (and marshmallow fluff if using) and stir until completely melted and smooth.

Remove from heat and stir in the vanilla extract. Fold in the puffed rice cereal until fully coated. Allow the mixture to cool for 2–3 minutes.

Shape the Treats:
For bars (as shown in the photos), press the warm mixture firmly into a parchment-lined 8×8 pan. Let it cool for 20–30 minutes, then cut into squares.
Optional: If you prefer bite-sized treats, lightly grease your hands and roll the mixture into 1–1.5 inch balls. Place them on a parchment-lined baking sheet to cool.

Melt the White Chocolate:
Add the white chocolate to a microwave-safe bowl and heat in 20–30 second intervals, stirring between each round until smooth. Add a little coconut oil if you want a thinner drizzle.

Decorate the Treats:
For bars, drizzle the melted chocolate over the tops of the squares.
For balls, dip the tops or roll each one lightly in the chocolate, using a fork to shake off any excess.
Immediately add holiday sprinkles before the chocolate sets.