Prepare the Rosemary Infused Bourbon:

Strip the leaves from the rosemary stem and place them in a small jar or glass.

Pour the bourbon over the rosemary leaves.

Allow the bourbon to infuse for at least 30 minutes. For a stronger rosemary flavor, you can let it infuse for up to 24 hours in the refrigerator.

Mix the Cocktail:

In a cocktail shaker, combine the rosemary-infused bourbon (strained), lemonade, egg white, and bitters.

Dry shake (shake without ice) vigorously for about 15 seconds. This helps to create a frothy texture from the egg white.

Add Ice and Shake Again:

Add a handful of ice to the shaker.

Shake again vigorously until the mixture is well chilled, about another 15 seconds.

Serve:

Strain the mixture into a chilled glass. You can use a fine mesh strainer to ensure no ice or rosemary bits make it into the glass.

Optionally, garnish with a small sprig of rosemary or a twist of lemon peel to enhance the presentation.

Enjoy:

Your Rosemary Bourbon Lemonade is ready! The herbal notes of the rosemary, combined with the richness of bourbon and the tanginess of lemonade, create a delightful spring cocktail.