Hachis Parmentier: Classic French Shepherd's Pie vs Hearty Cottage Pie with Creamy Potato Topping

Both dishes layer browned ground beef, onion, carrot and caramelized tomato paste beneath a buttery mash, but they diverge in seasoning and finish. The Hachis Parmentier simmers its filling covered with fresh thyme and bay leaf, then enriches the potatoes with egg yolk, nutmeg and extra butter before a layer of Gruyère bakes golden on top. The Cottage Pie adds celery, dried thyme and Worcestershire sauce, simmering uncovered into a thicker, more savory sauce under a simpler milk-and-butter mash, with Parmesan only optional. The result is a gently aromatic, cheese-topped pie versus a deeper, savory one with a golden, peaked crust.