In almost every screen there will be 3 cookies hidden in the environment.
When you press
a top menu bar will show...you can see the icon for cookies. Collect 10+ cookies, and eat them until the achievement unlocks. Only cavaet is that early in chapter 1, Bjorn will 'stop' eating cookies (giving help) for a certain story progressing to happen. After that, you can eat them again until you have consumed 10 of them.