The Best Scottish Shortbread

2 ½ cups all-purpose flour 1 cup butter, at room temperature ½ cup white sugar 1 tablespoon white sugar, or as needed Preheat the oven to 300 degrees F (150 degrees C). Mix together flour, butter, and 1/2 cup sugar in a bowl with your hands until well combined. Press dough into an ungreased 11 ½ x 7 ½-inch sheet tray or jelly…