Start by seasoning the meat with salt and pepper and browning it in a large skillet with olive oil over high heat. Make sure the skillet is very hot before adding the oil and that the oil is hot before adding the beef. Brown the meat on all sides.
Pour in the red wine and deglaze the pan. Scrape the bottom of the skillet to remove all that is stuck in the bottom. Transfer the meat along with the wine and juices to the pot of the slow cooker.
Add the onions, garlic, Dijon mustard, Worcestershire sauce, sliced mushrooms, fresh thyme, and 1 ½ cup beef broth. Cook on high for 4 hours, or on low for 8.
Make a slurry with the ½ cup beef broth remaining and the cornstarch, and add it to the crockpot 15 mins before the cooking time is over.
Once the sauce has thickened, unplug the slow cooker and stir in the heavy cream. Serve over freshly cooked egg noodles. Check the seasoning and add salt and pepper if needed.