Prep. Preheat your oven to 375°F (or 350°F for convection). Then, line two baking sheets with parchment paper and set aside.
Cream the wet ingredients. Cream the softened butter, shortening, and granulated sugar in a stand mixer. Start on low speed and gradually increase to medium-high, mixing for about 3 minutes until the mixture is light and fluffy. Then, scrape down the sides of the bowl, ensuring everything is fully combined. Next, add the egg and vanilla extract and mix at medium speed until incorporated. The mixture should be smooth and creamy.
Mix the dry ingredients. Whisk together the all-purpose flour, salt, baking powder, and baking soda in a separate mixing bowl. Gradually add the dry ingredients to the butter mixture, mixing at low speed until combined. Be careful not to overmix, as this can affect the cookie texture.
Shape the dough. Roll the dough into tablespoon-sized balls (the dough will be soft). Roll the dough balls in sugar and place them on the baking sheets about 2 inches apart. Gently flatten each ball with the bottom of a glass. Instead of rolling in sugar, you can sprinkle some sugar on after they are flattened on the baking sheet. Bake. Bake for 11-13 minutes or until the cookies are set and the edges start turning golden. They should remain light in color.
Cool the cookies. Once the cookies are done baking, let them cool on the baking sheet for about 5 minutes to firm up. After that, transfer them to a wire rack to cool completely.