In a large heavy pot, melt the butter over medium to low heat.

Stir in the brown sugar and marshmallows.

Stir until the mixture is almost completely melted.

Turn off the heat.

Stir in the vanilla.

Stir in the popcorn and mix until well coated.

Allow the mixture to cool enough so that it can be handled; make sure to coat your hands with butter or cooking spray when you are shaping them.

Scoop out the desired size of the popcorn ball and use your hands to shape the mixture into a ball.

Place the popcorn balls on a baking sheet lined with wax paper to cool.

Before they cool, sprinkle the tops of the popcorn balls with a small sprinkle of sea salt.

If you want to add a chocolate drizzle, simply melt some chocolate and drizzle it over the top of the popcorn balls before you add the sprinkles and salt.