Rinse quinoa under cold water and combine with vegetable broth in a medium saucepan. Bring to a boil, then reduce to a simmer, cover, and cook for 15 minutes. Set aside.

Heat butter or olive oil in a large skillet. Add chopped onion and minced garlic, sauté for 2-3 minutes. Incorporate broccoli, diced carrot, and chopped bell pepper; cook for 5-7 minutes.

In a separate saucepan, melt butter. Add flour, whisk until bubbly. Gradually whisk in milk and cook until thickened. Stir in shredded cheese until melted.

Combine cooked quinoa and sautéed vegetables with the cheese sauce. Season with dried herbs, salt, and pepper. Mix thoroughly.

Preheat oven to 375°F (190°C). Grease a casserole dish, pour in the mixture, and top with additional shredded cheese.

Bake for 25-30 minutes until golden brown and bubbly.

Let rest for 5-10 minutes, garnish with parsley or chives, and serve.