Fill a cocktail shaker with ice cubes and pour in the bourbon, freshly squeezed lemon juice, and simple syrup.
For a frothy texture, add an optional egg white.
Secure the lid on the shaker and shake well for about 30 seconds. Remember, if you're including the egg white, you'll need to shake without ice for the first 15 seconds, before adding the ice and shaking again.
Strain into a rocks glass filled with ice. Garnish with a maraschino cherry and a slice of orange.