01 - Place butter in a medium saucepan over medium heat. Cook, stirring constantly, until butter foams and develops golden-brown specks with a nutty aroma, approximately 4–6 minutes. Pour immediately into a large mixing bowl and cool for 10 minutes.
02 - Whisk brown sugar and granulated sugar into the cooled brown butter until fully dissolved. Add eggs one at a time, followed by vanilla extract, beating until smooth and glossy.
03 - In a separate bowl, whisk together flour, baking soda, baking powder, salt, cinnamon, nutmeg, and ginger until evenly distributed.
04 - Add dry ingredients to wet mixture and stir with a spatula just until flour streaks disappear. Do not overmix.
05 - Gently fold in oats, grated carrots, walnuts or pecans, and raisins if using until evenly distributed throughout the dough.
06 - Cover bowl and refrigerate for 30 minutes to enhance chewiness and prevent excessive spreading during baking.
07 - Preheat oven to 350°F. Line two baking sheets with parchment paper.
08 - Portion dough into 2-tablespoon balls, placing them 2 inches apart on prepared baking sheets.
09 - Bake for 11–13 minutes until edges are set and centers appear slightly underbaked. Cool on baking sheet for 5 minutes, then transfer to wire rack.
10 - Beat softened cream cheese and butter until creamy. Add powdered sugar and vanilla, mixing until smooth and drizzle-consistency. Drizzle over cooled cookies.