Bring a large pot of salted water to a boil and cook the egg noodles until just al dente. Reserve ½ cup of the pasta water, then drain and set aside.

Season the sliced chuck roast with the salt, pepper, garlic powder, and Worcestershire sauce.

Heat a large cast iron skillet over high heat. Add the olive oil and sear the beef in batches for 60–90 seconds, just until browned. Don't overcrowd the pan.

Transfer the beef to a plate.

Reduce the heat to medium and add the butter to the same skillet.

Add the sliced onions and cook for 10–12 minutes, stirring occasionally, until they're deeply golden and softened. The browned bits left from the beef will melt into the onions.

Add the garlic and cook for another minute.

Sprinkle the flour over the onions and stir constantly for 1 minute.

Slowly whisk in the beef broth, scraping up any browned bits from the bottom of the skillet.

Whisk in the Onion Soup Mix, Dijon mustard, and dried thyme. Bring to a gentle simmer and cook for 3–5 minutes, until slightly thickened.

Reduce the heat to low and stir in the heavy cream.

Add the white cheddar and Monterey Jack one handful at a time, stirring until smooth and creamy.

Return the beef (and any juices) to the skillet.

Add the cooked egg noodles and toss until everything is coated in the sauce.

If the sauce becomes too thick, stir in a splash of the reserved pasta water until silky.

Sprinkle the remaining ½ cup Monterey Jack over the top.

Place the skillet under the broiler for 2–3 minutes, just until the cheese is melted and lightly browned.

Top with chopped parsley and a generous handful of crispy fried onions before serving.