In the bowl of a stand mixer, beat together butter and peanut butter until combined.
Add white and brown sugar and beat for 2-3 minutes, until mixture is smooth and creamy.
Add egg and vanilla extract and mix again until combined.
In a medium bowl, combine flour, salt, and baking soda and whisk until combined.
Gradually add the dry ingredients to the stand mixer while mixing on low speed.
Do not overmix the dough.
Cover bowl with plastic wrap and chill in the refrigerator for 2-3 hours, until dough is firm enough to handle.
Preheat oven to 350F and line a baking sheet with parchment paper.
Use a 1 tbsp. cookie scoop to scoop cookie dough and roll into a ball.
Roll the cookie dough balls in white sugar and place on the baking sheet.
Press the cookies down with a fork to create a criss-cross pattern on the cookies.
Bake for 8-9 minutes and let cool on the baking sheet for 5 minutes before transferring to a wire cooling rack to cool completely.