I have found it works best for me to cook up our egg casserole, quiche, frittata about the same time dinner is going. Fortunately my kids will eat it cold, especially because it just appears on the table bright and early in the morning. We use an assortment of vegetables. Sometimes we change it up with fruit, bacon, or sausage.
I have also found when my kids are begging for pancakes, muffins, bread, or fritters, they are more than happy to make them in the afternoon. They can hardly wait for the next morning.
My kids also like to make some homemade granola out of seeds, but this can get a bit expensive. It is a fun treat.
I also try to have squash, plantains, or potatoes readily available for breakfast. This usually means I cook up a few on one night, along with the egg casserole, and when there are moans that breakfast was too small, we dish out the squash and potatoes. The plantains we will just cook up in the morning, but the kids love them so they are willing to wait.
We can’t do any oats, but can you do steel cut oats? There are some great overnight recipes for steel cut oats.