Creamy Chicken and Noodle Casserole

For the casserole:
6  tablespoons butter, divided
1/2  cup onion, diced
1/2  cup celery, diced
1/2  cup  carrot, diced
1  clove garlic, minced (1/2 teaspoon)
1 (8 ounce) package sliced mushrooms
1/2  teaspoon kosher salt
1/2  teaspoon black pepper
1/4  cup flour
1 1/2 cups chicken broth, low sodium
2  cups whole milk
3  tablespoons grated Parmesan Cheese
1 pound wide egg noodles, cooked and drained
3  cups cooked and shredded chicken
1  cup frozen peas, thawed
2  cups (8 ounces) shredded Cheddar Cheese


For the Topping:
2  tablespoons of reserved butter, melted
1  cup crushed Ritz Crackers, (about 20)
1  small can Durkee Onions, crushed


Melt 4 tablespoons butter in a large skillet over medium heat.  Add the chopped onion, celery and carrot.  Saute for 4-5 minutes until soft.  Add the garlic, mushrooms, salt and pepper. Saute until the mushrooms are soft and their liquid has evaporated.  


Sprinkle the flour in the skillet and cook for about 2 minutes until bubbly.  Slowly add the chicken broth and milk, bring the mixture to a boil, reduce heat and simmer for a couple of minutes until thickened.  Remove from the heat and stir in the Parmesan cheese, cooked egg noodles, shredded chicken and peas.


Pour 1/2 of the noodle mixture into a lightly greased 9 x 13 inch casserole dish.  Sprinkle with 1/2 of the cheese.  Cover with the rest of the noodle mixture and top with the remaining cheese.


In a medium bowl, mix the crushed crackers and Durkee onions with the remaining 2 tablespoons butter.  Sprinkle on top of the casserole.  Bake at 350 degrees for 25 - 30 minutes.