In small saucepan, over medium heat, swirl sugar, poire William and ginger until sugar is dissolved; cool. Mixture should come to a boil.
Remove and discard ginger.
Spoon 1 ½ tablespoons of syrup in each of 4 flute glasses.
Tilt glass and slowly pour in prosecco; gently stir.
Drop 1 blueberry, 1 raspberry and 1 pear slice in each glass.
Video
Notes
For garnish: peel and slice pears and cut with a small star shape cookie cutter.You can add a piece of lemon peel along with the ginger to create the simple syrup infusion.