Place the raisins in a medium bowl. Pour warm water over them and set aside to soak.

In the bowl of a stand mixer fitted with the paddle attachment, add the butter, light brown sugar, and granulated sugar. Mix on medium speed for 2 to 3 minutes, or until the mixture is fully incorporated and fluffy.

Add the eggs and vanilla extract. Mix until fully combined.

Turn off the mixer. Add the oats, flour, cinnamon, baking soda, and kosher salt.

Turn the mixer to low speed and mix until just combined.

Drain the raisins and add them to the dough. Mix until evenly distributed.

Cover the bowl and refrigerate the dough for 30 minutes, or up to overnight.

When ready to bake, preheat the oven to 350°F. Line baking sheets with parchment paper.

Using a 2-tablespoon cookie scoop, drop dough onto the prepared baking sheets, leaving about 2 inches of space between each cookie.

Bake for 11 to 12 minutes, or until the edges are lightly golden. The centers may look a little wet, but they will finish baking as they cool.

Let the cookies rest on the baking sheet for a few minutes before transferring them to a wire rack to cool completely.