Preheat oven to 350°F. Grease a 3-quart baking dish with butter or cooking spray; set aside.
Cook the noodles in a large pot of salted boiling water for 1 minute less than the package directions for al dente. Drain.
In a large bowl, combine turkey, condensed soup, milk, sour cream, garlic powder, onion powder, salt, pepper, and 1 cup of the cheese. Add the cooked noodles and frozen peas to the turkey mixture; stir to combine. Taste and season with additional salt and pepper, if desired.
Transfer the turkey and noodle mixture to the prepared baking dish. Sprinkle the remaining 1 cup of grated cheese over top.
In a small bowl, combine the cracker crumbs and the melted butter. Sprinkle over the top of the casserole.
Bake, uncovered, for 25-30 minutes, or until the top is golden brown and the filling is hot and bubbly.