Preheat your oven to 375°F (190°C) if you’re baking immediately.

Grease a 9x13-inch baking dish (or line with parchment for easier cleanup).

If using the panko topping, mix ½ cup panko breadcrumbs with 2 tbsp melted butter and set aside.

Heat 2 tbsp olive oil in a skillet over medium heat. Add the diced onion and sauté until translucent and sweet, about 5–7 minutes.

Add garlic and cook 30 seconds more (don’t let it burn — it should smell fragrant and golden).

In a very large bowl, combine the cooked chicken, cooked quinoa, frozen mixed vegetables, sautéed onion and garlic, ¾ cup shredded cheddar, yogurt or cottage cheese, condensed cream of chicken soup, beaten eggs, milk, thyme, oregano, smoked paprika, salt, and pepper.

Stir until everything is evenly distributed and creamy.

Taste a small spoonful of the mixture and adjust salt and pepper as needed.

If it tastes too thick, add another tablespoon of milk; if too loose, add a spoonful of cooked quinoa.

Spoon the filling into the prepared baking pan and spread into an even layer.

Sprinkle the remaining ¾ cup shredded cheddar over the top, then evenly scatter the panko-butter mixture.

If baking right away: cover loosely with foil and bake at 375°F for 20 minutes, then remove foil and bake another 12–18 minutes until bubbly and the top is golden.

Let the casserole rest for 10 minutes before serving so it sets.

If freezing: cover tightly with plastic wrap, then foil. Freeze up to 3 months.

To bake from frozen, remove plastic wrap, keep foil on, and bake covered at 375°F for 45–55 minutes, then remove foil and bake another 15–20 minutes until hot and golden.

For thawing overnight, thaw in the refrigerator and then bake covered at 375°F for 25–30 minutes, removing foil to bake for another 10–15 minutes.