Take the cupcakes out of the paper liners and place them in a bowl with 3/4 cup (175 mL) of the buttercream – you can stir with a spoon to mash the cake into the frosting, but it’s actually quicker to do so with clean hands. Use a small ice cream scoop to portion balls of the cake mixture and roll between the palms of your hands to make round. Place these onto a small parchment-lined baking tray or plate and freeze for at least 4 hours.
Melt the chocolate in a metal bowl placed over a pot with barely simmering water, stirring gently until smooth. Remove the bowl from the heat and transfer it to a deeper bowl (this makes it easier to submerge the cake pops. Insert a lollipop stick into each cake ball and dip it fully into the chocolate, shaking off any excess. Place the pops onto a clean, parchment-lined baking tray. The cold of the frozen cake centres should set the chocolate within a few minutes, or you can chill the cake pops for 5 minutes to set the chocolate.
Tint some of the remaining buttercream orange and spoon this into a piping bag fitted with a small flat leaf tip. Tint the other remaining buttercream green and spoon it into a piping bag fitted with a small plain tip. Hold a cake pop upright in one hand (and you will be able to see how the flat top becomes the top of the cauldron) and use the orange frosting to pipe flames at the base of the cake pop, coming up the cauldron from where the lollipop stick meets the cake pop. Use the green frosting to pipe bubbling “goo” on the flat top of the cauldron. Place a few jelly beans on top. Stick the decorated cake pops into an apple, pumpkin or a vase of sugar, to hold them upright. They can be served within 6 hours or refrigerated until ready to serve later on.