- 2 cups all-purpose flour
- 1/2 teaspoon baking soda
- 1/2 teaspoon salt
- 1 cup white sugar
- 1/2 cup butter, softened
- 1 egg, separated
- 1 teaspoon vanilla extract
- 1/2 cup buttermilk
- Preheat oven to 350 degrees F (175 degrees C). Line a baking sheet with parchment paper.
- Combine flour, baking soda, and salt in a bowl.
- Combine sugar, butter, egg yolk, and vanilla extract in a separate bowl; beat with an electric mixer until creamy. Add flour mixture in 3 batches, alternating with buttermilk; beat dough well after each addition.
- Clean beaters and beat egg white in a glass, metal, or ceramic bowl until stiff peaks form. Fold gently into the dough.
- Drop tablespoonfuls of dough onto the prepared baking sheet.
- Bake in the preheated oven until cookies just start to brown, 10 to 11 minutes.