Preheat oven to 375 F and spray square 9 x 9 baking dish with cooking spray. Set aside.
In a large bowl, add eggs, milk, olive oil, baking powder, salt, pepper and whisk to combine. Add oat flour and stir with a spatula. Then add spinach, feta cheese, parmesan cheese, green onion, dill, garlic and stir to combine until thick batter forms.
Transfer mixture into previously prepared baking dish, level with spatula and bake uncovered for 40 minutes or until toothpick inserted in the center comes out clean.
Remove from the oven and let cool for 30 minutes. Transfer brownies onto a cutting board and cut into 9 squares.
Enjoy warm or cold with a side salad.
Video
Notes
Store:Â Refrigerate leftovers in an airtight container for up to 5 days.
Freeze: Freeze leftovers for up to 3 months, individually wrapped in a resealable bag or in an airtight container. Can freeze sliced or unsliced. Thaw on a counter for 1-2 hours or in the fridge overnight.
Reheat: Reheat brownie in a microwave, toaster oven or bake in regular oven at 350 degrees for 15 minutes.