Place all of the ingredients in a large bowl and stir to combine. Grease a 7x10 pan (or 9x13 if you want to double the recipe). Pour the oatmeal mixture into the pan and cover with lid or foil. Place in the refrigerator overnight.
In the morning, uncover the pan and place in a cold oven. Bake at 350 for 40-45 minutes or until set in the center. Let cool 5-10 minutes before serving.
You can serve this as pictured or scoop it into bowls. I like mine broken up like warm granola in a bowl and my kids prefer to eat theirs like a slice of cake. However you cut it, it is good. Enjoy!
Notes
FREEZER MEAL: Let the oatmeal cool completely and then cut or scoop into portions. Store the oatmeal in airtight freezer bags or containers. Reheat in the microwave with a tablespoon of water.