Step 1Over a small bowl, crush the kumquats using a citrus press, a muddler or a mortar and pestle. Discard any seeds and place the kumquat juice, crushed skins and the simple syrup into a flute. Slowly pour in 1 ounce of Prosecco; swirl to mix. Add the remaining Prosecco, letting the foam settle. Slowly pour Port over the back of a spoon directly over the Prosecco to create a layered effect.