Grease or butter a 9×13 baking dish; set aside.
Lightly beat the eggs in a mixing bowl, and then add the remaining ingredients except the oats. Mix well. Add the oats, and stir to fully incorporate.
Transfer the mixture to the prepared baking dish. Cover with plastic wrap and allow the oatmeal to rest for 1-4 hours. (It can sit on the counter for up to 2 hours but should be refrigerated for longer periods.) This will give the oats time to plump up. (If you’re short on time, you can bake immediately; you may need to add a few extra minutes to the cooking time.)
When ready to bake, uncover the oatmeal and preheat the oven to 375 degrees F. If the oatmeal has been refrigerated, allow the baking dish to sit on the counter while the oven preheats. Bake for 30 minutes, give or take a few based on individual oven, or until just firm in the center.
May serve with warmed milk, additional nuts, and/or sliced bananas. It’s delicious eaten plain, too.
Cover and store leftovers in the refrigerator. Reheat gently in the microwave or enjoy cold.