Place strawberries and sugar into medium saucepan over high heat.
Mash strawberries as they begin to soften.
Bring to a boil and then turn heat down to a simmer. Simmer for about 30 minutes, until reduced by half. Stir frequently and watch closely to avoid burning.
Let cool completely.
CUPCAKE:
Preheat oven to 350°F. Line muffin tin(s) with liners.
In large bowl, add the flour, baking powder and salt; mix to combine.
Cream the butter.
Add in the sugar and mix until light and fluffy.
Add one egg at a time, beating in between each addition.
Add the flour mixture and buttermilk, alternating each addition.
Add vanilla and strawberry puree. Mix completely to combine.
Pour batter into muffin cups, filling each muffin cup to ¾ full. Bake 25-30 minutes, or until toothpick inserted in the center comes out clean.
Remove from oven; let cool completely.
BUTTERCREAM:
Cream butter until pale yellow.
Add in the marshmallow cream and vanilla and continue mixing.
With mixer on low, add the powdered sugar one spoonful at a time.
ASSEMBLY:
Take cooled cupcakes out of muffin tin.
Fill piping bag with buttercream. For piping the ghosts, use a large round tip (the one used here was Ateco #808).
Pipe each cupcake with buttercream to create “ghost.” Pipe a large dollop onto the cupcake, followed by a medium dollop, and then a small dollop to form the ghost.
With tweezers or fingers, gently place the sugar pearls on each ghost for the eyes and mouth.