Add the raisins to a small bowl and cover with warm tap water then soak for 10 minutes. This will soften the raisins and allow them to plump before baking. After soaking, drain them well and blot with a paper towel.
Preheat the oven to 350° then line a baking sheet with parchment paper.
In a large bowl using a hand mixer cream the butter, brown sugar, granulated sugar, eggs and vanilla until smooth.
In a small bowl whisk the flour, baking soda and cinnamon. Add the dry ingredients to the butter/sugar mixture and blend by hand (not the mixer) and when that’s combined, stir in the oats and raisins.
Refrigerate the dough for 15 minutes.
Add 1 1/2" balls (I used a scooper) onto the prepared baking sheet leaving about 2″ between each cookies. Bake 10-12 minutes or until they’re golden on the edges. They'll still look a little under-baked in the middle. Cool on the baking sheet 2 timed minutes then transfer to a wire cooling rack.