Preheat oven to 350°F. Line baking sheets with parchment paper or silicone liners.
Whisk together the flour, baking powder, baking soda, and salt. Set aside.
Using an electric mixer on medium speed, beat the butter, cream cheese, sugar, and brown sugar until light and fluffy. Add the egg and vanilla, and mix well. Mix in the peanut butter.
Reduce mixer speed to low. Gradually add the flour mixture, mixing just until combined.
Drop the dough by tablespoonfuls onto the prepared pans. Use a fork to make a crosshatch pattern on top of the cookies.*
If desired, sprinkle the top of each cookie with a pinch of sanding sugar.
Bake 12 to 15 minutes, or until the cookies are lightly browned. Cool on the pan for 5 minutes. Then transfer the cookies to a wire rack to cool completely.
*Dipping the fork in a little bit of flour will help keep it from sticking to the dough.
Number of cookies yielded may vary depending on the size of the cookies.
Remember, cooking times may vary depending on ovens, so test doneness before stated cooking times.