Line 2 large trays with baking paper.
Break the chocolate part off of each Mikado then break that part in half (so you'll get 2 chocolate covered 'legs' from each stick). Repeat until you have 72-96 'legs' in total (6-8 for each spider).
Add the butter, cocoa powder and mini marshmallows to a saucepan. Place it over low heat and stir gently until melted. Make sure to mix it properly so there are no white streaks left.
Remove it from the heat and stir in the Rice Krispies.
Leave the mixture to cool in the pan for about 5 minutes, or until you're able to pick it up without it sticking to your hands.
Take spoonfuls of the mixture and roll into balls (you should end up with about 12 in total). Place them onto your lined tray.
Melt the milk chocolate. Dip the end of each 'leg' into the melted chocolate then gently push them into the Rice Krispie balls using a twisting motion.
Stick two edible eyes onto each ball using the melted chocolate as your glue.
Let them sit at room temperature for 2 hours until completely set then enjoy!