To make simple syrup with kirsch for the Haunted Black Forest Layer Cake, stir in 1/3 cup kirsh after boiling syrup.
Heat sugar and 1/2 cup water in a small saucepan over medium-high heat, stirring frequently, until sugar has dissolved. Bring to a boil. Let cool completely. Syrup can be refrigerated in an airtight container up to 1 month.