Using a 4"/10cm wide Mickey Mouse head-shaped cookie cutter, cut out 20 Mickey Mouse brownies from the sheet of brownies.
Place the brownies onto a wire rack over a cookie sheet.
Place the chocolate wafers in a large microwave-safe bowl and microwave for 45-second increments, mixing after each time, until the chocolate has completely melted.
Carefully pour the chocolate over the Mickey brownies to completely cover them.
Gently tap the wire rack onto the cookie sheet to allow the extra chocolate to drip off the brownies.
Allow the chocolate to harden before removing the brownies from the wire rack.
If using Wilton tubes of frosting, attach a round no.3 piping tip to the tube of white frosting, or alternatively, squeeze the frosting into a piping bag fitted with the same size tip.
Pipe a spider web in the bottom corner of each brownie.
Pipe three lines up from the bottom right or left, then curved lines between each straight line. Use the image below as a guide.
Repeat step 7 with the tube of black frosting.
Use the black frosting to pipe a medium-size circle for the spider's body, then a smaller circle for the spider's head.
Pipe spider legs on the sides of the body.
Allow the frosting to harden before serving. Enjoy and Happy Halloween!