01 - Preheat oven to 375°F. Lightly grease a 9x13-inch baking dish with oil or nonstick spray.
02 - In a large skillet over medium heat, warm olive oil. Add bell peppers, zucchini, mushrooms, and red onion. Cook for 5 to 6 minutes until vegetables are softened. Add spinach and cook until wilted, about 2 minutes. Remove skillet from heat.
03 - In a large mixing bowl, combine thawed hash browns, sautéed vegetables, shredded cheddar cheese, and cottage cheese. Mix gently until evenly distributed.
04 - In a separate bowl, whisk together milk, chickpea flour, baking powder, garlic powder, smoked paprika, salt, and black pepper until smooth and lump-free.
05 - Pour the milk mixture over the potato and vegetable mixture. Stir thoroughly until well combined and evenly coated.
06 - Spread mixture evenly into prepared baking dish, smoothing the top with a spatula.
07 - Place baking dish in preheated oven and bake for 40 to 45 minutes, or until the top is golden and set.
08 - Remove from oven and let cool for 10 minutes before slicing. Garnish with chopped parsley if desired. Serve warm.