Fill your cocktail shaker with plenty of ice and then add the Aperol, Campari, Tequila and orange juice.
Shake hard for 30 seconds. Have a taste – do you need to adjust for sweetness? Add the sugar syrup and shake again.
Strain into the chilled glass. Add a drop of orange bitters and top up with chilled Prosecco. Garnish with a slice of orange and small sprig rosemary and enjoy.