Preheat the oven to 350 degrees and line a cookie sheet with parchment paper. Set aside.
Put the oats in the food processor and pulse a few times until the oats become coarsely ground (not fine).
In a medium bowl, add the processed oats, flour, baking powder, baking soda, cinnamon, nutmeg, and salt. Mix well.
In another large bowl, use an electric mixer to cream the butter, sugar, and brown sugar until the mixture becomes creamy—about 2 minutes.
Add the eggs one at a time, whisking well after each addition.
Using a spatula or wooden spoon, stir in the dry ingredients and the raisins until thoroughly combined. You will have a thick and sticky dough.
Use a cookie scoop to drop the dough onto prepared cookie sheets. Leaving about 2 inches of space between each cookie dough. (The cookies will spread).
Bake for 15 minutes or until the edges become brown. Rotate the pan halfway between for even doneness.
Leave the cookies to rest in the pan for at least 5 minutes before transferring them to the cookie rack.
Remove from oven and let cool on the pan for 5 minutes.