Working with one cookie at a time, pipe an outer circle of black icing onto the cookie, just slightly inside the outer edge of the cookie. You want to leave a little bit of room for dragging the icing outwards.
Fill in the circle with black icing.
As soon as the circle is full, take the white icing and pipe a dollop in the center of the cookie. Pipe concentric circles of white icing around the dollop, leaving some space in between each circle.
Take a toothpick and begin to drag it through the icing, starting at the center dollop and making lines outwards to the edge of the cookie. Only drag from the middle outwards, otherwise the cobweb will look more like a flower! You may want to wipe excess icing off the toothpick in between each line you make, so that the colors don’t begin to blend together.
Repeat with the remaining cookies, then allow the cookies to dry at room temperature for about 6 hours or overnight.
You can stop at this point, but if you’d like to add spiders, do so now while the cookies are drying! Line a baking sheet with parchment paper and pipe spiders with the remaining black icing. Allow them to dry until they are completely firm, about 2-3 hours. They will take less time to harden than the cookies because of the smaller surface area.
Once the spiders have dried, take a small dish and combine 1 tsp of black edible glitter with 1-2 drops of lemon extract. Mix until the glitter has dissolved and looks like metallic, liquidy paint.
Use a clean paintbrush to paint the glitter onto the spiders. Allow the paint to dry to the touch at room temperature, then set aside until the base cookies have dried.
Gently peel the spiders off the parchment paper and use a tiny amount of excess icing as glue to attach them to the web cookies. Enjoy!