In a large mixing bowl, whisk together the all-purpose flour, granulated sugar, powdered sugar, baking powder, baking soda, and salt until well combined.
Transfer the mixture to an airtight container or a large resealable plastic bag for storage.
To make sugar cookies from the mix, preheat your oven to 350°F (175°C).
In a separate bowl, combine 1 cup (2 sticks) of softened unsalted butter, 1 large egg, and 1 teaspoon of vanilla extract. Beat until creamy.
Gradually add 2 cups of the sugar cookie mix to the butter mixture, mixing until a soft dough forms. If the dough is too sticky, add more mix 1 tablespoon at a time.
Roll the dough into 1-inch balls and place them 2 inches apart on an ungreased baking sheet. Flatten each ball slightly with the bottom of a glass or your hand.
Bake for 8 to 10 minutes or until the edges are lightly golden.
Remove from the oven and allow the cookies to cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.