Line a baking sheet with parchment paper or wax paper and set it near your work area.

Place the white candy melts or chopped white almond bark in a microwave-safe bowl. Microwave in 20–30-second intervals, stirring thoroughly after each interval, and stop when the coating is nearly smooth so residual heat can finish melting it.

Dip each Oreo into the white coating, turning it with a fork until completely covered. Lift the cookie out, gently tap the fork against the bowl to remove excess coating, and place the cookie on the lined baking sheet.

Melt the dark chocolate wafers separately using short microwave intervals and frequent stirring. Transfer the melted chocolate to a small piping bag, a zip-top bag with one corner snipped off, or a squeeze bottle.

While the white coating is still wet, pipe three or four concentric dark chocolate circles on each cookie. The circles can be slightly uneven; a handmade pattern adds to the spooky charm.

Immediately drag a toothpick from the center of the cookie toward the outer edge, repeating around the cookie to create the web. Wipe the toothpick between pulls if chocolate begins collecting on it.

Add Halloween sprinkles or candy eyes while the coating is still soft, if desired. Let the cookies set at room temperature or refrigerate them for 10–15 minutes until firm.