Prepare a baking sheet with parchment paper or a silicone mat and set aside.
Using your preferred method, pop your popcorn and set aside in a large bowl.
8 cups popped popcorn
Pro tip: If you need to, you can even use a bag of microwave popcorn, popped according to package directions. If you use this method, omit the pinch of salt.
In a medium saucepan, combine sugar, butter and corn syrup. Stir constantly over low heat until butter is melted and combined.
3/4 cup granulated sugar, 1/2 cup unsalted butter, 1/4 cup light corn syrup
Add marshmallows and stir constantly until melted and combined.
10 ounces mini marshmallows
Remove from heat and add cinnamon and rum (and salt, if adding). Stir to combine.
1 tablespoon ground cinnamon, 2-3 teaspoons rum, Pinch salt
Pour mixture over popcorn and use a spatula to stir and coat.
Spray your hands with nonstick spray and form balls 3 to 4" in diameter. Place each ball on prepared baking sheet to set. If you desire, stick a popsicle stick in the top of each ball, pushing it about halfway in.
Popsicle sticks
Let set completely, serve, and enjoy!
Notes
Storage: These are definitely best if eaten the same day, but can be stored in an airtight container or resealable bag in the fridge for up to 5 days. Just make sure they're not touching, otherwise they'll stick together! You can wrap them individually in plastic wrap or parchment paper tied at the top (that would make an adorable way of packing them to look like little popcorn ball pumpkins, btw) and store them in the container/bag to avoid that issue.