01 - Preheat oven to 350°F. Line two baking sheets with parchment paper.
02 - In a medium bowl, whisk together flour, cinnamon, nutmeg, baking soda, and salt. Set aside.
03 - In a large bowl, cream together butter, brown sugar, and granulated sugar until light and fluffy.
04 - Beat in eggs one at a time, then add vanilla extract.
05 - Gradually mix in the dry ingredients until just combined. Stir in oats and raisins until evenly distributed.
06 - Drop rounded tablespoons of dough 2 inches apart onto the prepared baking sheets.
07 - Bake for 12-14 minutes, or until edges are golden and centers are set. Cool on the baking sheets for 5 minutes, then transfer to a wire rack to cool completely.
08 - For the caramel frosting, melt butter in a small saucepan over medium heat. Add brown sugar and milk, stirring until dissolved. Bring to a gentle boil, then remove from heat.
09 - Whisk in powdered sugar and a pinch of salt until smooth and spreadable.
10 - Spread or drizzle caramel frosting over cooled cookies. Allow frosting to set before serving.