Boozy, tart whiskey sour popsicles with a marbled bitters-and-aquafaba foam swirl, made with an alcohol ratio precise enough to actually freeze solid.
Keep the bourbon at or below 1/2 cup for an 8-mold batch — more than that and the pops stay too soft to fully set. Swap bourbon for rye if you want a spicier finish, or for a kid-friendly version, cut the bourbon to 2 tablespoons and add an extra 1/2 teaspoon bitters plus 1/4 teaspoon vanilla to keep the depth of flavor. Aquafaba can be swapped for 2 tablespoons pasteurized egg white if you prefer, but skip raw, unpasteurized egg white entirely since the mixture is never cooked. Pops keep well for up to 2 weeks tightly wrapped in the freezer.