You can use gluten-free flour such as buckwheat flour, but I haven't tried it. However, I think it may work well.
I use Dutch-processed cocoa powder and have not tried this recipe with natural cacao powder.
Instead of chocolate chips, you can use a bar of chocolate and cut it into small bits.
You can also prepare the cookie mixture and leave it in the fridge for up to 2 days before baking. Let it sit at room temperature for at least 20 minutes before forming into balls.
If you want to bring your milk to room temperature fast, heat it at medium heat for 1-2 minutes or for a few seconds in a microwave. However, the milk should not be hot.
Make sure you measure all of the ingredients correctly. I found this article helpful.