Preheat the oven to 350F, line 2 the baking sheets with parchment paper.
Beat the butter with a hand mixer with sugar and vanilla for 1 minute.
Add one egg and beat until smooth.
Add flour, baking powder, and salt, mix with a mixer.
Add oat flakes and raisins, mix with a spoon.
With an ice cream spoon place balls of dough onto a baking sheet, leave room between them because they will spread while baking.
Bake for 10-15 minutes, check a few times. The cookies should be golden brown.
Cool for 2-5 minutes on a baking sheet and transfer to a wire rack to cool completely.
