The Best Flourless Peanut Butter Cookies

large egg

creamy classic-style peanut butter or honey-roasted peanut butter (Jif, Skippy, or similar rather than natural or homemade versions. Sometimes natural versions work fine but not always; classic peanut butter is more trustworthy. I use honey-roasted.)

light brown sugar, packed

granulated sugar

vanilla extract

baking soda

salt