Muddle the Blackberries: In a cocktail shaker, muddle the fresh blackberries to release their juices.

Add Ingredients: Add the vodka, fresh lemon juice, simple syrup, and egg white (if using) to the shaker.

Dry Shake: If using egg white, shake the mixture without ice for about 10 seconds to create a frothy texture.

Shake with Ice: Add ice to the shaker and shake vigorously for about 20 seconds.

Strain: Double strain the mixture into a rocks glass filled with ice. Use a fine mesh strainer to catch the blackberry seeds.

Garnish: Garnish with a lemon wheel or a fresh blackberry.