Preheat oven to 375 degrees F. Line rimmed baking sheets with parchment paper.
In a saucepan add carrots and cover with water. Cook until softened. Drain off the water and mash. Allow cookies to cool completely. I used a small food processor to mash them up and didn't mind a few small chunks.
In the bowl of an electric stand mixer, cream sugar and butter together. Add 1 egg and 1 cup of cooled, mashed carrots.
In a medium bowl, add flour, baking powder, salt, and baking powder. Whisk to combine.
Slowly add dry ingredients to wet ingredients. Mix to combine. Add hazelnuts.
Using a 1-1/2 tablespoon scoop, drop cookies onto baking sheet.
Bake 12 to 15 minutes or until edges brown slightly. Remove cookies to a cooling rack to cool completely.
Mix glaze ingredients together and stir until sugar is dissolved. Add more juice to thin or more sugar to thicken. Drizzle or dip cookies with glaze.
This recipe was calculated using the exact brands and measurements I used to make this recipe. If you are following a strict diet please note changing anything will cause the nutritional info to change. My calculations are intended as a guide only.