I baked my horse some cookies for his birthday recently and got the recipe online.. I can't remember exact quantities but you can tell when it's a proper mixture that you can roll out etc. It made quite a few as well and they keep for a week in an airtight container.
Ingredients:
Molasses
Porridge oats
Plain flour
Grated carrot/apple/swede
Water
Then cut into shapes and bake for about 15 mins until golden.
I think that's it... you might want to look for a proper recipe though!