Preheat your oven to 350°F. Line two baking sheets with parchment and set aside.
Combine your butter, granulated sugar, and brown sugar in a large mixing bowl. Use an electric mixer to beat the ingredients together on high speed until smooth.
Add the egg, beat again until it's thoroughly combined with the creamed sugar. Reduce the speed of your hand mixer and gently whisk in the flour, baking powder, baking soda, and cinnamon.
Fold in the shredded carrots, making sure that they are evenly distributed throughout your cookie dough. Use a large standard size cookie scoop or a large spoon to drop balls of cookie dough onto a baking sheet. Bake for 11 minutes.
Let your cookies cool on the pan for a few minutes and then transfer them to a wire cooling rack for 20 minutes. While your cookies are cooling, prepare your frosting. Whisk together the cream cheese and powdered sugar until smooth and creamy.
Use a piping bag or spatula to frost your cookies and then top them with the crushed walnuts. Serve and enjoy!
Notes
Store leftover cookies in an airtight container in the fridge for up to 5 days. Cookies can be frozen for up to 2 months.