1. Preheat oven to 180C (356F) for 10 minutes.
2. Mix butter with electric mixer on medium speed until soft.
3. Add cookie mix and milk into the mixing bowl, continue mixing on medium speed for 5 minutes until the ingredients become cookie dough.
4. Add eggs to the mixing bowl, continue to mix on low speed for 1 minute until the eggs are blended into the dough.
5. Mould, or use a cookie cutter, to create the desired shape. (A diameter of 5 to 6cm is recommended for each cookie).
6. Place a baking sheet, and then the cookies, on an oven tray.
7. Bake for 20 minutes at 180C (356F). To ensure even baking, flip cookies after 10 minutes if your oven only has heating coils above.
8. Rest cookies for 10 minutes on a cooling rack.
9. Cookies can be kept in an airtight container for about 1 month, so you can give your dog a treat a day!