Mix peanut butter, sugar, vanilla and egg in a bowl until very well incorporated and smooth. It should still be firm enough to make into 1” balls. Allowing it to sit an extra five minutes will give the sugar some time to be better absorbed into the other ingredients. That'll prevent the feeling of sugar crystals in the cookies. 

Place balls on cookie sheet, and flatten each dough ball creating lines in the center with a fork until about 1/4” thick.

These cookies will expand out slightly so you have to leave enough room in between the cookies to prevent them from merging together as they bake. I would leave 1” between each cookie.

Bake for approximately 13 minutes at 350 degrees. Keep in mind that every oven is different. Check on your cookies and remove them from the oven when fully baked and even colored.

When ready, remove from oven.