Using a stand mixer or a hand held electric mixer, cream the butter, sugar and brown sugar.
Add in the peanut butter and mix well.
Add in the egg, vanilla and salt. Mix to combine.
Using a wooden spoon or a spatula, mix in the flour. Once incorporated, add in the oatmeal and raisins and stir to combine.
Cover the bowl and chill in the fridge for at least 30 minutes.
Preheat the oven to 350°F. Line a baking sheet with parchment paper.
Using an ice cream scoop, scoop the cookie dough into the baking sheet, leaving 2 inches between the cookies. If you want your cookies flatter, press the top of the cookies just a little bit with your fingers.
Bake in the oven for 12 minutes until the edges are golden brown.
Let the cookies cool before serving them.