1.Preheat oven to 180°C/350°F. Grease oven trays; line with baking paper.
2.Beat butter, sugar and egg yolk in a small bowl with an electric mixer until combined. Transfer to a medium bowl. Stir in carrot, then combined sifted flour, soda and cinnamon. Stir in oats and enough milk to make a firm dough.
3.Using damp hands, roll heaped teaspoons of mixture into balls. Place balls 5cm (2-inches) apart on trays; flatten into 3cm (1¼-inch) rounds.
4.Bake cookies for 15 minutes or until golden; cool on trays.
Cookies will keep in an airtight container for up to 1 week.Note