Bring all ingredients to hand. Separate one large egg white if you prefer to omit raw egg whites for dietary reasons; substitute 0.5 oz aquafaba for a vegan version. Stack 6 fresh basil leaves and clap them between your palms once to release aromatics; set aside one small leaf for garnish.

Dry shake

In a cocktail shaker, add 2 oz botanist-style dry gin, 0.75 oz fresh lemon juice, 0.5 oz simple syrup, 0.25 oz green chartreuse, 0.25 oz St-Germain, the egg white, and the bruised basil leaves. Seal the shaker and shake vigorously without ice for 15–20 seconds to emulsify the egg white and integrate the botanicals. This creates a foamy texture.

Wet shake

Add about 1 cup of ice to the shaker. Shake vigorously for another 12–15 seconds until the shaker feels very cold and the exterior is frosty. The ice chills and dilutes the cocktail to the proper balance.

Double strain

Open the shaker and double-strain the cocktail through a fine-mesh strainer into a chilled coupe or Nick & Nora glass that contains about 1/2 cup fresh ice if you prefer it slightly chilled on the rocks (for a more classic presentation omit the ice and serve neat). Double-straining removes basil bits and gives a smooth texture.

Garnish and finish

Express the oils from a lemon twist over the foam and rub the peel around the rim, then drop it into the drink or rest on the glass. Gently lay the reserved basil leaf onto the foam (or skewer it with a cocktail pick). Add optional micro herbs or an edible flower on top for a refined presentation. Serve immediately.

Notes

If using aquafaba, shake a bit longer during the dry shake to achieve proper foam. Adjust simple syrup to taste if you prefer a drier or sweeter profile. Green chartreuse is potent — you can reduce to 0.125 oz if you want a subtler herbal accent.