Classic Cocktail

I am looking for a recipe for a classic champagne cocktail sugar cubes and bitters. Thanks!?
Champagne Cocktail 6 oz Champagne cold 1 sugar cube Angostura bitters, sugar cube soaked with Angostura bitters. Place the bucket on the bottom of a glass of champagne. Fill with champagne. Garnish with a lemon twist.
How To Make A Tom Collins Classic Cocktail