Preheat oven to 350°F. Lightly spray a 9x13 casserole dish with cooking spray.
In a large mixing bowl, add Greek yogurt, milk, peanut butter, eggs, maple syrup and vanilla extract. Stir well with a rubber spatula.
In another medium bowl, add oats, hemp seeds, cinnamon, baking powder and sea salt. Stir well to combine.
Add dry ingredients to the large mixing bowl with wet ingredients, and gently stir to mix.
Gently fold in frozen berries. Once combined, add the mixture to your casserole dish and spread evenly.
Place in the oven and bake for 40-45 minutes, until center is cooked and top is golden brown in color. The edges may be slightly darker brown.
Remove from the oven and let it cool for 5-10 minutes, then cut and serve. If desired, top with extra peanut butter drizzle, fresh berries or additional Greek yogurt. Enjoy!