Meanwhile, prepare the frosting. Using a hand mixer, cream together the room temperature butter and cream cheese on medium-high speed until completely smooth. Mix in vanilla extract and sea salt. With mixer running on low speed, slowly add powdered sugar and beat until well blended and smooth. Chill the frosting while the cupcakes finish cooling.
Frost completely cooled cupcakes with cream cheese frosting and decorate to look like Halloween creatures: FOR THE GHOST: Pipe the cream cheese frosting (using a plain #24 piping tip) onto the cupcake in an upside-down cone shape. Place two mini chocolate chips near the top of the frosting for the eyes!
FOR THE GREEN MONSTER: Dye the cream cheese frosting green and using a #17 tip create short quick actions (while applying pressure) to add “fur” to the cupcake. Add edible eyes wherever you want on top!
FOR THE PURPLE MONSTER: Dye the cream cheese frosting purple and using a #17 tip create short quick actions (while applying pressure) to add “fur” to the cupcake. Using the frosting, pipe a short action on two marshmallows and attach 2 edible eyes. Using toothpicks, attach the marshmallows to the cupcakes.
Halloween cupcakes best enjoyed within 1-2 days.