While prepping your ingredients, soak raisins in warm water for 10-15 minutes (optional, but recommended for soft, plump raisins). Drain before using.
Preheat oven to 350°F (177°C). Line two baking sheets with parchment paper and set aside.
In a medium bowl, whisk together your dry ingredients:
1 cup all-purpose flour, ½ tsp baking soda, ½ tsp ground cinnamon, ¼ tsp nutmeg.
Set aside.
In a large bowl, cream ½ cup softened unsalted butter, ⅓ cup brown sugar, and 2 tbsp granulated sugar for 2–3 minutes, until light and fluffy.
Add 1 large egg and 1 tsp vanilla extract to the butter mixture. Mix well for about 1 minute.
Gradually mix in the dry ingredients until fully combined.
Fold in 1 cup old-fashioned rolled oats, followed by the soaked raisins.
Using a cookie scoop, portion dough into mounds (about 2 tablespoons each) and place on the baking sheets, spaced about 2 inches apart.
Bake for 9–11 minutes, or until edges are lightly golden and centers are just set.
Cookies will continue to firm up as they cool.
Allow to cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.