For the ginger honey syrup, combine one cup honey, one cup water, and one large knot of ginger (about six inches long, peeled and thinly sliced) in a saucepan over high heat.

Bring to a boil, stirring occasionally, then reduce heat to medium and simmer five minutes. Remove from heat and chill in the fridge overnight, then strain through a fine mesh sieve, discarding solids. Use immediately or store in the fridge.

For the cocktail, combine all but the champagne in a shaker with ice. Shake vigorously for 15 seconds, then strain into a chilled flute and top with champagne or cava.