Lamb shepherd's pie

Pasos

1. Peel the potatoes, cut them into even pieces, and cook them in a large pot of salted water until they yield without resistance to the tip of a knife.
2. Meanwhile, finely dice the onion, cut the carrots and celery into small dice, and mince the garlic; sweat everything in the oil with a knob of butter until the vegetables become tender and slightly glossy.
3. Add the ground lamb and brown it, breaking it up with a spatula until it is no longer pink and begins to catch in places.
4. Stir in the tomato paste, let cook until it darkens slightly, then dust with flour and mix until the meat is well coated.
5. Pour in the brown stock, add the Worcestershire sauce, thyme, rosemary, and bay leaf, then simmer gently until you get a thick, glossy, and coating sauce.
6. Remove the herbs, add the peas off the heat, then adjust the salt and pepper; the filling should be flavorful, juicy, but not liquid.
7. Drain the potatoes, let them dry briefly in the hot pot, then mash them with the butter and hot milk until you get mashed potatoes that are soft but firm enough to hold up in the oven.
8. Spread the lamb filling in a baking dish, cover with the mashed potatoes, score the surface with a fork, then bake until the edges are bubbling and the top is golden in places.
9. Let rest for a few minutes before serving, so that the sauce sets and the portions hold together better on the plate.