Preheat oven to 350°F. Grease a 9×13 pan.
In a large bowl, whisk together the eggs, milk, vanilla, and melted oil (or butter).
Then add in all dry ingredients and mix well.
Pour the mixture into the greased pan and top the oats with the bag of frozen berries.
Bake uncovered for about 45 minutes or until oats are tender and the mixture is set. The edges are typically browned.
Serve immediately in a bowl with a splash of milk, drizzle of honey, or eat plain. Cover and refrigerate any leftovers to reheat later.