Cream together softened butter, cane sugar, and brown sugar
Beat in room temperature egg and vanilla extract
In a separate bowl, whisk together all-purpose flour, cocoa powder, baking powder, baking soda, and salt
Combine dry ingredients with wet ingredients
Fold in semi-sweet chocolate chips and mini marshmallows
Bake cookies according to recipe instructions
For marshmallow frosting, beat room temperature butter with marshmallow fluff
Mix in powdered sugar and vanilla extract until smooth
Frost cooled cookies with marshmallow frosting
Drizzle with melted chocolate wafers
Top with holiday sprinkles
