In a small bowl, combine the raisins and rum. Cover and heat in a microwave for about 1 minute, or just until the rum starts to bubble. Stir the bowl to make sure all the raisins are resting in the hot rum. Allow to sit until the raisins are at room temperature and plump, about 20 minutes.

In a large bowl, whisk together the flour, oats, baking soda, baking powder, salt, cinnamon, and nutmeg. Set aside.

In a stand mixer fitted with the paddle attachment, cream the butter and sugars on medium speed until light and fluffy, about 3 minutes.

Add the eggs, one at a time, beating on medium speed after each addition, until incorporated. Add the flour mixture all at once and mix until just incorporated. Mix in the raisins with any remaining rum. You may need to give the mixing bowl a couple of swipes with a rubber spatula at the end to make sure the raisins are evenly distributed.

Line a baking sheet with parchment paper. Scoop the cookie dough using a #20 (3-tablespoon) portion scoop onto the baking sheet. Flatten the cookie balls into ¾-inch disks. You can make the cookies larger or smaller, but it will affect the baking time.

Refrigerate the dough disks for at least 30 minutes; if you have the time, they improve if you let them sit for 24 to 36 hours. After they are chilled, you can bake them or freeze them for baking later.

Preheat the oven to 350°F / 175°C, with racks in the top and bottom thirds of the oven. Line two baking sheets with parchment paper.

Evenly space six chilled cookies on each sheet. Bake in the oven with one sheet on the top rack and the other on the bottom rack for about 10 minutes. Rotate the baking sheets tops to bottoms and continue baking for about 5 more minutes.

Allow the cookies to cool for a few minutes on the baking sheet and then move to a cooling rack.