Preheat & Prep: Preheat oven to 350°F (175°C). Line a baking sheet with parchment paper or a silicone baking mat.
Mix Dry Ingredients:In a large bowl, whisk together flour, oats, baking powder, baking soda, cinnamon, nutmeg, ginger, and salt. Set aside.
Cream Butter & Sugar: In another bowl, beat together butter, brown sugar, and granulated sugar until light and fluffy (about 2–3 minutes). Add the egg and vanilla extract, and mix until smooth.
Combine Wet & Dry:Gradually add the dry ingredients to the wet mixture, stirring just until combined. Do not overmix.
Fold in Carrots & Add-Ins: Gently fold in grated carrots and any nuts, raisins, or coconut if using.
Scoop & Bake: Scoop dough onto the prepared baking sheet, spacing them 2 inches apart. Shape slightly with fingers if needed. Bake for 10–12 minutes or until edges are lightly golden and centers are set.
Cool: Allow cookies to cool on the baking sheet for 2–3 minutes, then transfer to a wire rack to cool completely before frosting.
Make Frosting: Beat cream cheese and butter together until smooth. Add powdered sugar and vanilla extract, beating until fluffy.
Frost: Once cookies are completely cool, spread or pipe the cream cheese frosting on top. Garnish with chopped nuts if desired.