I'm not a PB&J fan, and only use peanut butter in baking or a peanut sauce. Once I open a jar, it could sit for a long, long, time. I ran across "Peanut Butter Powder" on a shopping site yesterday, and my first reaction was to wrinkle my nose and wonder what the food industry will over-process next. I've made my own once or twice, but not sure it will work (flavor and consistency) in cookies. I read through the instructions on how to substitute the powder for the real stuff, but I'm not a convert yet, and am still thinking that open jar, even if it's thrown away after months squirreled away in the back of the fridge, is a better option. But before I totally reject the product...???