Combine gin, sage-infused simple syrup and ice in a shaker. Shake and strain over ice in a Highball glass. Fill with Prosecco (amount determined by glass size), and stir gently. Garnish with cucumber slices and a sage sprig.
*To make the sageinfused simple syrup:
Combine equal parts sugar and water and bring to boil. Lower heat, toss in a few sprigs of sage, then reduce by 1⁄3 to 1⁄2 until you achieve syrup consistency. The color should be a pale greengold color.