The Winterized Penicillin

Bring ginger, honey, and 1 cup water to a simmer in a small saucepan over medium-low heat. Cook, stirring, until honey has dissolved. Gently simmer, uncovered, 30 minutes. Strain through a fine-mesh sieve into a small bowl; discard solids. Let cool to room temperature.

Combine blended scotch, grapefruit juice, and 1 oz. honey-ginger syrup in a cocktail shaker filled with ice. Cover; shake vigorously until outside is frosty, about 20 seconds. Strain into a rocks glass, preferably with a single large ice cube. Top off with single malt scotch.

Cooled ginger-honey syrup can made 2 weeks ahead. Store in an airtight container and chill.