Combine 1/2 cup granulated sugar and 1/2 cup water in a small saucepan. Add a small handful (about 12 g) of fresh mint leaves. Heat over medium, stirring, until sugar dissolves. Simmer 1 minute, remove from heat, let steep 15 minutes, then strain out mint leaves and cool. Yields about 3–4 tablespoons.

Assemble Punch Base

Juice watermelon

If using whole watermelon, cube about 6 cups of watermelon and puree in a blender until smooth. Strain through a fine-mesh sieve into a bowl or pitcher to yield approximately 4 cups of clear juice, pressing solids to extract liquid.

Combine spirits and juices

In a large (2–3 quart) punch bowl or pitcher, add 2 cups Towpath Vodka, 4 cups fresh strained watermelon juice, and 1 cup freshly squeezed lime juice. Stir gently to combine.

Sweeten

Add 3 tablespoons mint simple syrup to the punch base. Taste and adjust: add up to 1–2 additional tablespoons if you prefer sweeter or less-tart punch.

Chill and Add Sparkle

Chill

Cover the punch and chill in the refrigerator for at least 30 minutes to let flavors marry. If pressed for time, add plenty of ice at serving instead.

Add Prosecco & Sparkling Water

Just before serving, pour in 750 ml chilled Prosecco and 2 cups chilled sparkling water (optional for lighter bubbles). Stir gently once to combine; avoid vigorous stirring to preserve Prosecco bubbles.

Garnish & Serve

Prepare bowl

Add 1 large block of ice or plenty of ice cubes to the punch bowl or individual glasses to keep the punch cold without rapidly diluting it.

Add fruit and herbs

Float 2 cups of seedless watermelon cubes or small slices, 6 lime wheels, and a dozen fresh mint sprigs on top of the punch for aroma and visual appeal.

Serve

Ladle punch into chilled glasses, making sure each glass gets a bit of fruit and a mint sprig. Offer extra lime wheels and mint on the side. Keeps well refrigerated for up to 6 hours; add more Prosecco just before serving if the fizz diminishes.