In a saucepan, bring vegetable broth to a boil. Add quinoa, reduce heat to low, cover, and let simmer for 12–15 minutes until absorbed. Fluff and set aside.

Heat olive oil in a skillet. Add onion and garlic; sauté for about 2 minutes until fragrant.

Add bell pepper, zucchini, mushrooms, and cherry tomatoes. Cook for 5–7 minutes until softened.

Stir in baby spinach along with oregano, basil, smoked paprika, salt, and pepper. Cook until spinach wilts.

In a bowl, combine tomato sauce, Greek yogurt, and red pepper flakes to create a creamy sauce.

Preheat oven to 190°C (375°F). In a large bowl, mix cooked quinoa, sautéed vegetables, and creamy sauce until coated.

Pour mixture into a greased 9x13 inch baking dish. Sprinkle mozzarella and Parmesan on top.

Cover with foil and bake for 20 minutes. Remove foil and bake for an additional 10 minutes until cheese is bubbly.

Let casserole rest for 5 minutes. Garnish with parsley or basil before serving.