In a large pot on the stove, melt the butter and marshmallows together. Stir in the vanilla and peanut butter until it's smooth and creamy. Take it off the heat.

Pour the popcorn into a big bowl. Pour the marshmallow mixture over the top and mix it all up—it'll be a bit sticky.

Now, grease up your hands with some oil or butter to keep the marshmallow mix from sticking, then shape the mixture into 12 balls.

Line 'em up on a plate or baking sheet, and you're ready to enjoy these tasty treats!