In the bowl of a stand mixer cream together butter and sugars until a paste forms. Add in vanilla and egg and mix well.
Add the oats, flour, cinnamon, baking soda, salt, and nutmeg and mix until just combined. Be careful not to over mix!
In a food processor, pulse the shredded carrots until they are in tiny little chunks. If you don't have a food processor you can also mince them with a knife. You do not want big shreds of carrots in these delicate little cookies so take the time and don't skip this step!
Gently fold in the carrots and raisins.
If the dough is a little stiff you can loosen it up with 1 tsp of milk.
Scoop cookies by rounded tablespoon onto a lined baking tray and bake at 325 for 9-11 minutes or until golden brown. (You want them to still be slightly soft so they're easy to bite into. Don't over bake until crunchy!).
Move to a cooling rack and cool completely before frosting.
For the Frosting
Add vanilla and cold cream cheese into a stand mixer and beat on medium speed until fluffy.
Add powdered sugar 1/2 a cup at a time mixing well after each addition.
Once powdered sugar is completely incorporated add SOFT, room temperature butter and beat until well combined.
For the Sandwich Cookies
Frost the bottom of one of the carrot cookies, then place another cookie on top to make a sandwich. Repeat with all remaining cookies. Keep refrigerated. Enjoy.