For the froth: Add the lemons, sugar and ¾ cup water to a blender. Blend until smooth, then strain the mixture through a fine mesh strainer.
For the drink: Add ice to an all-purpose wine glass. Pour in the amaro and 1 ½ ounces lemon froth and stir to combine (save the remaining lemon froth for another use). Top with the Champagne and garnish with the lemon twist.
