In a medium saucepan, bring all ingredients to a boil over medium-high heat. Reduce heat to medium-low, and simmer until thickened, syrupy, and reduced by about two-thirds, 25 to 30 minutes. Let cool completely, then refrigerate overnight. Refrigerate in an airtight container until ready to use.
Recipe by Bake from Scratch at https://bakefromscratch.com/pomegranate-molasses-gingerbread-cake/