Last year I visited my friend Eva in Milwaukee. She made baked oatmeal for breakfast and it was yummy. From time to time I made it on a weekend as something different. Eva based her oatmeal on this recipe from Cookie and Kate, with just a couple of adjustments required to make it vegan: omit the egg (it doesn’t need to be replaced with anything) and use vegan margarine in place of the butter.
The batch I made recently used soy milk and homemade almond milk, instead of coconut milk. I also used mixed frozen berries instead of the blackberries suggested by the recipe. I used a little less cinnamon and a little less maple syrup than suggested. I also ended up making only half a batch, since I had only 1 cup of rolled oats in the cupboard, and it was just enough for the 4 of us.
I only baked my oatmeal for about 20 or 25 minutes, not 45 minutes as suggested. Possibly the shorter time was enough because I had only made a half batch, so the mixture wasn’t very deep. But I suspect you might not need 45 minutes even with the full quantity.
Three of us really liked this: Child #2 did not. But that made Child #1 happy because they got to eat all of Child #2’s leftovers!