First, preheat your oven to 350F and grease a 9x13" baking dish with cooking spray. Set aside. Bring a large pan to medium heat. Once hot, add oil. Then, add mushrooms and onion and spread out evenly in the pan. Season with salt & pepper and let cook, undisturbed, for 3 minutes. Flip/stir and continue cooking for 2 more minutes. Add in the spinach and stir until wilted, about 1 more minute. Remove the pan from the heat.
½ tbsp avocado oil, ½ medium yellow onion, 8 oz baby bella mushrooms, 2.5 oz baby spinach, kosher salt & black pepper
Add eggs, cottage cheese, garlic, kosher salt & black pepper to a blender and blend until just combined - this should happen really quick, and over-blending adds unwanted air bubbles into the mixture.
10 large eggs, 1 cup plain cottage cheese, 2 small garlic cloves, 1 tsp kosher salt, ½ tsp black pepper
Pour egg mixture into the prepared baking dish and then add in the sautéed veggies and feta. Stir around with a spatula to spread the veggies out evenly. Then, transfer to the oven and bake for about 30 minutes, or until the middle feels firm and set. It may puff up in the oven if there are trapped air bubbles but don't worry, it'll go back down once it cools.
½ cup crumbled feta
Cut the egg bake into 6 pieces and enjoy! To meal prep this, allow it to cool down completely before transferring to an airtight container and storing in the fridge.