Strawberry Shortcakes

Name: Strawberry Shortcakes
Ingredients: 1½ cups all-purpose flour; 1½ Tbsp. granulated sugar; 1½ tsp. baking powder; Rounded ¼ tsp. kosher salt; ¼ tsp. baking soda; ½ stick (2 oz.) cold unsalted butter, cut into ½ cubes; ¾ cup well-shaken buttermilk; 1 Tbsp. milk or cream for brushing; 2½ lb. strawberries, trimmed and quartered (7½ cups); ⅓ to ½ cup granulated sugar, or to taste; ¼ tsp. kosher salt; 1 cup chilled heavy cream; ¼ cup sour cream; 1½ to 2 Tbsp. powdered sugar; ½ tsp. vanilla extract; Potato masher