Place green candy melts in a bowl and microwave on 50% power (defrost mode) for 2 minutes. Stir well, then continue heating in 1-mintue intervals on defrost mode, stirring in between, until fully melted.

Fill the serial killer candy mold with the melted green candy melts and place in freezer until set.

Next, melt the black candy melts the same way starting with 2 minutes on 50% power, then 1-minute intervals, stirring in between until smooth.

Lay out a piece of parchment paper on the counter.

Dip each Oreo into the black candy melts, letting the excess drip off before placing on the parchment paper. Quickly add a green head onto each dipped Oreo while coating is still wet, then finish with sprinkles.

Allow cookies to dry before serving.