@Gargron hope you're going to post a picture! Grated choc is a really good thing to do in cookies - in america it was made famous in these: https://cooking.nytimes.com/recipes/9465-the-250-cookie-recipe

The one cooking tip I think is golden is to do with the difference between Baking Soda & Baking Powder:

Soda Spreads
Powder Puffs

Hope your cookies turn out!