I prefer steaming the oats in a bowl in the top of a pot with boiling water below and a lid on it.
No stirring, no boiling over. You would put oats and milk in a bowl, place on a rack in a steamer/large covered pot, and boil the water in the pot.
I don't recall ever getting a burnt layer before I tried this, but I cook them in water and add milk/cream/yogurt after they are cooked if adding milk/cream/yogurt - so the boiling milk could be part of your issue. Excess heat might also be part of the issue (usual reason for scorched/burnt layers of whatever on the bottom of the pot) - notably milk can burn, where water won't. But plenty of folk scorch rice in water with simply too much heat. You also don't mention stirring - which is essential when not steaming in my experience (which is a major reason why I now steam.)