"It's really all about the gravy...."
(12-oz.) package egg noodles
butter
vegetable oil
boneless skinless chicken breasts, cut into 1" pieces
Kosher salt
Freshly ground black pepper
extra-virgin olive oil, divided
baby bella mushrooms, thinly sliced
large onion, chopped
cloves garlic, minced
fresh thyme leaves
low-sodium chicken broth
dijon mustard
Worcestershire sauce
cornstarch
sour cream, plus more for serving
freshly chopped parsley