01 - Preheat oven to 375°F. Lightly grease a 9x13-inch baking dish with olive oil or butter.
02 - Prepare quinoa according to package directions until fluffy and cooked through. Set aside.
03 - Heat olive oil in a large skillet over medium heat. Sauté diced onion until soft, about 3 to 4 minutes. Add minced garlic and cook for 1 minute. Add broccoli florets and sauté until just tender, about 5 minutes for fresh or until heated through for frozen.
04 - In a large mixing bowl, whisk together eggs, milk, sour cream, dried thyme, paprika, salt, and pepper until smooth. Fold in cooked quinoa, sautéed vegetables, and 3/4 cup of the shredded cheese.
05 - Pour the mixture into the prepared baking dish, spreading evenly. Top with the remaining 1/4 cup shredded cheese and breadcrumbs, if using.
06 - Bake uncovered for 30 to 35 minutes until the top is bubbly and golden brown. Let rest for 5 minutes before serving.