Bring butter to room temperature so it will be easy to use. Mix the eggs and vanilla extract.
Cream the butter with a hand mixer, then add brown sugar. Mix well until the mixture becomes white and thick.
Add the mixture of the eggs and vanilla extract from Step 1, and mix well. It becomes thicker and heavy at this point.
Change to a wooden spatula. Add the dry ingredients in one go, and fold in.
Add oatmeal and raisins, and fold in with a cutting motion. It seems like there's a lot of oatmeal, but don't worry.
It will blend like this.
Roll into 3 cm balls with 2 spoons, and place on a baking sheet.
Bake in the preheated oven at 180 / 355 for about 15 minutes, and it's done. They will become 5 cm diameter cookies.