To make the garnishes, spear the basil and mozzarella onto a wooden skewer and push to the bottom. Next, add prosciutto to the skewer, then layer with another mozzarella ball. Repeat until each skewer has 3 mozzarella balls and 2 pieces of torn prosciutto.
To mix the cocktail, first pour 1 ounce of balsamic vinegar into each highball glass. Add 2 basil leaves to each glass and gently muddle. Add 1 ounce of whey each and stir.
Fill the glasses with ice and pour 2 ounces vodka in each. Add 3 ounces Clamato and stir well to combine the liquids in the glass. Once combined, top each glass with 2 ounces sparkling water.
To serve, add the skewered mozzarella to the glasses with a straw, then garnish with extra basil.