📋 Instructions

1. 1Caramelize the onions — Melt the butter in a large oven-safe skillet over medium-low heat (about 300°F / 150°C pan temperature), add the onions and 1/2 teaspoon salt, and cook 20 minutes, stirring every few minutes, until deep golden brown and jammy.
2. 2Brown the beef — Push the onions to the side, raise the heat to medium-high (about 375°F / 190°C) and add the beef, breaking it up and cooking 6 to 7 minutes until no pink remains and the edges are browned.
3. 3Build the sauce — Stir in the Worcestershire, pepper and thyme, pour in the beef broth and bring to a simmer for 3 minutes until it smells rich and savory.
4. 4Par-cook the noodles — Meanwhile, boil the egg noodles in salted water for 2 minutes less than the package says, then drain; they should still have a firm bite in the center.
5. 5Combine everything — Fold the drained noodles into the skillet, taste and add salt if needed, then smooth the top into an even layer.
6. 6Add the cheese and crumbs — Scatter the Gruyère over the top, then toss the panko with a teaspoon of melted butter and sprinkle it over the cheese.
7. 7Bake until bubbling — Bake at 400°F (200°C) for 20 to 25 minutes, until the edges bubble and the top is golden brown; an instant-read thermometer in the center should read at least 165°F (74°C).
8. 8Rest and serve — Let the casserole rest 10 minutes so the sauce sets, then scoop and serve hot.