Mix, prepare & bake cupcakes to package directions
Cool completely on wire rack & prepare frosting
Cream softened butter & shortening in stand mixer with paddle attachment until smooth.
Blend in vanilla.
Add 1/2 the confectioners sugar & most of the milk - stir slowly until moist- then whip until well combined.
Add remaining confectioners sugar & milk.
Beat on med-high about 3-4 minutes scraping sides of the bowl occasionally.
The texture should be very smooth.
Using a large open star tip, pipe frosting in a swirl pattern on top of cupcakes
Add several spiders on top of frosting & serve.