In a large bowl, beat together the butter, brown sugar, eggs, and vanilla.
In a small bowl, mix together the flour, baking powder, baking soda, cinnamon, nutmeg, and oats.
Add the dry ingredients to the large bowl of wet ingredients and mix just until blended.
Add in the carrots, pecans, and the raisins and stir to combine. This dough will be sticky.
Place the dough in the refrigerator for 15 minutes.
Line a baking sheet with parchment paper and scoop cookies on the sheet 2" apart. I use a golf-ball sized cookie scoop so they are all the same size. Since this is a sticky moist dough, I wouldn't recommend using your fingers to scoop the dough.
Bake for 12-14 minutes until you see tiny bubbles start forming on the tops of the cookies and the edges start to darken slightly. Let the cookies cool completely before icing.
The Icing
Add the softened butter, softened cream cheese, and vanilla to a bowl and beat with a mixer until combined.
Add in the powdered sugar and mix with a spatula. The icing will seem thick at first but mix until it's smooth. You don't want it to be runny or it wont sit up in between the cookies.
Take one cookie (Careful! They are very moist and soft!) and scoop a tablespoon of icing in the center. Take the second cookie and press it gently onto the icing until you can see it coming towards the edges.
Eat right away or store in the fridge and let come to room temperature before enjoying. Do not stack them. They will stick together. (I know, I know...they're stacked in my photos. That's how I know this! lol)