Chill your glass. Pop a coupe or rocks glass in the freezer while you gather ingredients. A cold glass keeps the drink crisp.
Measure your ingredients. Add whiskey, lemon juice, and simple syrup to a cocktail shaker. If using egg white or aquafaba, add it now.
Dry shake first (if using egg white/aquafaba). Shake without ice for about 10–12 seconds.
This builds a nice foam and blends the texture.
Add ice and shake again. Fill the shaker with ice and shake hard for 12–15 seconds. You want the outside of the shaker to frost up.
Strain. Double strain into a chilled coupe for an “up” drink, or into a rocks glass over a large cube. Double straining keeps out ice shards.
Garnish. Express a lemon or orange peel over the top and drop it in.
Add a cherry if you like. Serve immediately.