Preheat the oven to 350 degrees. Prepare a 9x13 pan with butter, oil, or cooking spray. If you’re using a nonstick pan, you can skip this part.
In a bowl, mix the first 4 ingredients until incorporated.
Next, add the next four ingredients, mixing thoroughly.
Pour the oatmeal mixture into your pan. Bake for about 35 minutes, up to 45 minutes. You want the edges to be golden brown and the center to be set.
Let the oatmeal bake rest for five to ten minutes before serving. The berries retain a lot of heat!