Combine the warm milk, active dry yeast, and sugar in a bowl. Let sit for 5–10 minutes until lightly foamy. Add the flour, salt, eggs, and softened butter. Mix until a rough dough forms, then knead for 8–10 minutes until smooth, elastic, and slightly tacky. Kneading to a smooth, elastic consistency is what develops the gluten structure needed to trap gas evenly during rising, which is directly responsible for a roll with an open, soft crumb rather than a dense one.

Place the dough in a lightly greased bowl, cover, and let rise until doubled, about 1 hour to 1 hour 15 minutes. Do not rush the rise. Underproofed rolls bake dense and squat instead of soft and open. Letting the dough reach a genuine doubling, rather than cutting the time short, gives the yeast enough time to produce the volume of gas needed for a properly light, airy crumb once baked.

Divide the dough into 4 equal pieces. Shape each piece into a tight hoagie roll, about 18–20cm long. Place on a parchment-lined tray. Cover and let rise again for 45–60 minutes, until puffy and visibly lighter. Shaping the dough tightly, rather than loosely, is what gives the finished roll a cohesive, even crumb structure and a defined shape that holds together well once sliced and loaded with beef.

Preheat the oven to 190°C. Bake the rolls for 18–22 minutes, until golden-brown and cooked through. Cool before slicing. If you cut hot bread, the crumb compresses and turns gummy. Bread continues setting internally for a period after it leaves the oven — slicing while still hot disrupts that final structural setting, compressing the still-soft crumb into a denser, gummier texture than the same bread would have once fully cooled.

Pat the beef dry. Season all over with kosher salt, black pepper, garlic powder, and onion powder. Let it sit at room temperature for 30–45 minutes before roasting. Cold beef cooks unevenly and gives you an overdone outside with a cold centre. A roast straight from the refrigerator has a large temperature gradient to overcome — letting it temper first narrows that gap, so the exterior doesn't overcook by the time the heat has fully penetrated to the centre.

Heat the neutral oil in a heavy skillet or roasting pan over medium-high heat. Sear the beef on all sides until browned, about 6–8 minutes total. This browning is where the au jus gets depth. Pale roast beef gives weak jus. The fond left behind on the pan's surface after this sear becomes the foundation the au jus is built on — scraping that browned residue up later during the jus-making process carries directly into the finished dipping liquid's flavour.

Transfer the beef to a 160°C oven and roast until the centre reaches 50–52°C for medium-rare, or 54–56°C for medium. Rest for 20 minutes before slicing. After resting, slice as thinly as possible against the grain. Do not overcook the beef. French dip with grey, dry beef is a waste of bread and cheese. The extended 20-minute rest matters more here than for many other roasts given how thin the beef will eventually be sliced — a properly rested roast holds its juices through that thin slicing, while an unrested one loses much of that moisture onto the board the moment it's cut.

In the same pan, melt the butter over medium heat. Add the shallots or onion and cook for 4–5 minutes until softened and lightly browned. Add the garlic and cook for 30 seconds. If using flour for a slightly fuller jus, sprinkle it in and cook for 1 minute. Add the red wine and scrape up the browned bits from the pan. Simmer for 2–3 minutes. Add the beef stock, Worcestershire sauce, soy sauce, bay leaf, thyme, and black pepper. Simmer for 15–20 minutes until savoury and dark amber. Strain if you want a clean dipping jus. Taste and add salt only if needed. The au jus should be thin, savoury, and beefy — not thick gravy. Turning it into gravy misses the point. Using the same pan the beef was seared in means every bit of that browned fond gets deglazed and dissolved directly into the jus — this is the single most direct way the beef's own concentrated flavour ends up in the dipping liquid rather than staying stuck to the pan.

Add the sliced roast beef to a shallow pan with a few ladles of hot au jus. Warm gently for 30–60 seconds. Do not boil the sliced beef. Boiling ruins the pink interior and turns the meat tough. This brief warming is about bringing the already-cooked, thinly sliced beef back up to serving temperature, not cooking it any further — a hard boil at this stage would push the meat past medium-rare and tighten its texture considerably.

Split the hoagie rolls. Spread the cut sides lightly with butter and toast under the broiler or in a skillet until golden and lightly crisp. The roll needs structure. Untoasted bread will collapse once it hits hot beef and jus. A lightly crisped interior surface gives the roll real resistance against both the warm beef's residual moisture and any jus that soaks in during dipping, buying it considerably more structural integrity than an untoasted roll would have.

Pile about 150g warm sliced beef into each toasted roll. Add Swiss and provolone over the beef. Place under the broiler for 1–2 minutes, just until the cheese melts and pulls slightly. Do not broil so long that the beef cooks further and dries out. This brief broiler stage is calibrated purely to melt the cheese quickly — the beef is already at its correct doneness and temperature, so extended broiling only risks drying it out further with no benefit.

Cut each sandwich in half. Serve immediately with a small cup of hot au jus beside each sandwich for dipping. Serving the jus separately for dipping, rather than pouring it directly over the assembled sandwich, is what keeps the roll's edges crisp between bites — dip as you eat so the roll stays crisp at the edges.