Root Beer Float Cookies

Name: Root Beer Float Cookies
Ingredients: 6 cups all-purpose flour; 1 teaspoon baking soda; 1 teaspoon baking powder; 3/4 teaspoon kosher salt; 1 cup unsalted butter (room temperature); 2 cups packed light brown sugar; 3 eggs; 2 teaspoons root beer concentrate; 1 ¼ cups sour cream; Reynolds Kitchens® Parchment Paper with SmartGrid®; ½ teaspoon pure vanilla extract; 3/4 teaspoon root beer concentrate; 4 cups confectioners' sugar; pinch of salt; 6 tablespoons heavy cream; shimmer white sugar crystals for decorating (if desired)