I set a heatproof bowl over a saucepan of gently simmering water, making sure the bowl doesn't touch the water. I add the chocolate and stir it often so it melts evenly without scorching. If I'm in a rush, I microwave it in 15-second bursts instead, stirring between each round.
Once the chocolate is smooth, I pour it straight onto my parchment-lined baking sheet. Using an offset spatula, I spread it into an even layer, about a quarter to a half inch thick. I don't stress over a perfect shape here — rustic edges are part of the charm.
I move fast at this stage because the chocolate starts firming up quickly. I scatter candy corn, sprinkles, and candy eyeballs over the top, pressing lightly so everything sticks into the chocolate instead of rolling off.
I leave the pan at room temperature for about two hours, or pop it in the fridge for 30 minutes if I want it ready sooner. Once it's firm, I break it into rustic pieces with my hands or a sharp knife.