Soft Carrot Cake Cookies with Cream Cheese Frosting

Carrot Cake Cookies
0 Start by lining a cookie sheet with parchment paper and setting it aside.
1 In a medium bowl, whisk together the dry ingredients: flour, cornstarch, cinnamon, nutmeg, baking powder, and salt.
2 Cream the sugars and butter at medium speed in a large mixing bowl for about 2 minutes until light and fluffy. Scrape down the sides of the bowl as needed.
3 Whisk in the egg, egg yolk, and vanilla extract, mixing until fully combined. Gradually add the flour mixture to the wet ingredients, mixing on low speed until just combined. A few streaks of flour are okay.
5 Fold in the grated carrots gently with a rubber spatula. 
7 Scoop dough using a 3-tablespoon cookie scoop and place the balls on the prepared baking sheet. Cover with plastic wrap and refrigerate for at least 1 hour or up to 24 hours.
8 Preheat your oven to 350°F (175°C) when ready to bake. Place the chilled dough balls on a cookie sheet, spacing them 3 inches apart. Bake for 13-17 minutes until the edges are golden brown.
9 Optional, for perfectly round cookies: As soon as your cookies are out of the oven, use a circular cookie cutter slightly bigger than your cookies (or anything circular and hollow) and make a circular motion to swirl the cookies around inside the cookie cutter. You can also use a spatula to push in the uneven edges until you have a perfectly round cookie.
10 Let the cookies cool on the sheet before transferring them to a wire rack to cool completely.
Cream Cheese Frosting
11 Beat butter, vanilla, and salt until fluffy, about 1 minute.
12 Mix in cream cheese just until combined. Add powdered sugar and beat until smooth. Avoid overmixing.
13 Spread frosting on top of each completely cooled cookie and sprinkle with chopped walnuts.