Prep your work area by laying out a few strips of parchment paper.
Transfer the dark chocolate to a microwave safe bowl and heat for 30 seconds at a time. Stir well between increments until smooth. Transfer the melted chocolate to a piping bag or a ziploc with a small hole cut in the end.
To make the spiders: Pipe a small dot about the size of a dime and then four legs on both sides of the dot. Allow to set by placing the parchment with the spiders on a plate or cutting board and placing in the fridge or freezer to expedite the chocolate hardening.
Once the spiders are set, you can create the webs. Lay out approximately 8-10 pretzel sticks in a circle, with the points all meeting in the center.
Melt the white chocolate in a microwave safe bowl and heat for 30 seconds at a time. Stir well between increments until smooth. Transfer the melted white chocolate to a piping bag or a Ziploc with a small hole cut in the end.
Pipe a large dollop in the center of the pretzels to keep them all connected. Then pipe large circles around and around the pretzels until it resembles a web. Keep the white chocolate drizzle lines somewhat thick - if they are too thin, they are easier to break.
Immediately top with a spider (carefully remove from the parchment as to not break off any legs) and a few sprinkles for some color.
Repeat this process with the remaining pretzels until the white chocolate is gone.
Allow to set at room temperature for about 10-20 minutes or until the white chocolate has hardened.