Preheat your oven to 350°F (175°C) and coat a 9x13 baking dish with cooking spray.

Season chicken with salt, pepper, and paprika in a mixing bowl. Let marinate while heating oil.

Heat olive oil in a Dutch oven over medium-high heat. Cook seasoned chicken for 5-7 minutes until cooked.

Sauté onion, celery, and carrots for 5 minutes until softened. Add garlic and sauté for an additional 30 seconds.

Add sliced mushrooms and cook for 5-6 minutes until golden brown. Return chicken and veggies to the pot.

In a saucepan, whisk cornstarch and chicken broth over medium heat. Add melted butter and flour to create a roux.

Gradually add milk, chicken bouillon, and seasonings. Simmer for 5 minutes until thickened.

Combine the thickened sauce with the chicken and vegetable mixture, then fold in cooked wild rice. Transfer to the baking dish.

Sprinkle cheddar and parmesan cheese over the casserole, then mix panko breadcrumbs with melted butter and oil. Top the casserole.

Cover with foil and bake for 30-35 minutes. Allow to cool for 10-15 minutes before serving.