Place the raisins in a medium bowl. Pour warm water over them and set aside to soak.
To the bowl of a stand mixer with the paddle attachment, add the butter and sugars. Mix on medium speed for 2-3 minutes, or until fully incorporated and fluffy.
Add in the eggs and vanilla. Mix until combined.
Turn the mixer off. Add oats, flour, cinnamon, baking soda, and salt.
With the mixer on low, mix until just combined.
Drain the excess water from the raisins. Then, mix them into the cookie dough.
Cover and refrigerate the dough for 30 minutes, or up to overnight.
When ready to bake the cookies, preheat oven to 350°F. Line baking sheets with parchment paper.
Using a 2-tablespoon scoop, drop dough onto the lined baking sheets, leaving about 2 inches between each.
Bake for 11-12 minutes or until the edges are lightly golden. The top of the cookie may appear a little wet, but they will continue to bake out of the oven.
Let the cookies rest on the baking sheet for a few minutes before transferring them to a wire rack to cool completely.