Preheat oven to 400°F/200°C.
Cook noodles according to package instructions, rinse with cold water and set aside.
In a small bowl, combine the crushed crackers with ¼ cup parmesan cheese, and 2 tablespoons melted butter. Mix and set aside. That’s the buttered crumbs topping.
In a skillet, melt 2 tablespoons of butter, sauté onion until soft and translucent. Add mushrooms, season with salt and pepper and cook for 4-5 minutes or until softened.
Add flour, and cook for 1 minute. Pour stock over the flour, whisk and bring to a boil.
Reduce to a simmer, cook for a few minutes to thicken then stir in the cheddar cheese and ¼ cup of parmesan. Add the turkey, and peas. Stir in the lemon juice and season with salt and pepper. Stir so that everything is well combined (if using a different dish to bake in, transfer to the baking dish). I used a Le Creuset 11 inch shallow casserole dish, it’s 3 ½ qt. 9x13 dish can also be used.
Top with the buttered crumbs, and bake for 20 minutes.