1 1/4 cups (275 grams) unsalted butter, at room temperature
2 cups (400 grams) lightly packed brown sugar
1/2 cup (100 grams) granulated sugar
2 teaspoons pure vanilla extract
2 large eggs, at room temperature
1/2 cup (50 grams) loosely packed sweetened coconut flakes
Pour the rum over the raisins and let soak for at least 30 minutes or up to 24 hours. The longer you let them soak the more flavor the raisins will soak up.
Whisk together the rolled oats, flour, cinnamon, baking powder, baking soda, salt, and black pepper in a bowl. Set aside.
In a stand mixer fitted with the paddle attachment, cream the butter and both sugars on medium speed until light and fluffy, about 3 minutes. Mix in the vanilla. Add the eggs, one at a time, beating on medium speed until incorporated. Add the flour mixture all at once and mix just until incorporated. Mix in the raisins and coconut. You may need to give the bowl a couple of swipes with a rubber spatula at the end to make sure everything is evenly distributed.
Using a portion scoop, scoop cookie dough onto a baking sheet lined with parchment paper. I used a 3-ounce (83-gram) scoop. You can make the cookies larger or smaller, but it will affect the baking time. Refrigerate the dough for at least 1 hour, but they improve if you let them sit for 24 to 36 hours. After they are chilled you can bake them or freeze the dough balls for later baking.
Preheat the oven to 350°F with racks on the top, center, and bottom third of the oven. Line 2 baking sheets with parchment paper. Bake 6 evenly spaced cookies on each sheet in the middle of the oven for about 10 minutes. Rotate the baking sheets top to bottom and continue baking for about 5 more minutes. Allow the cookies to cool slightly on the baking sheets and then transfer to a rack to cool.