Shepherd's Pie with Lamb Ragu and Brown Butter Mash

Finely dice the onions, carrots, and celery. Mince the garlic. Finely chop the rosemary leaves and strip the thyme leaves. Peel the potatoes, cut into even 4 cm chunks, and hold in cold water until needed.

Heat the oil in a large, heavy-based oven-safe skillet or casserole over high heat until shimmering. Add the lamb mince in a single layer without stirring and cook for 6–8 minutes until a deep brown crust forms on the underside, then break up and stir.

Push the lamb to the sides of the pan, reduce heat to medium, and add the onions, carrots, and celery to the centre. Cook for 10–12 minutes, stirring occasionally, until the vegetables are softened and beginning to colour.

Add the garlic, tomato paste, rosemary, and thyme and cook for 2 minutes, stirring constantly, until the paste darkens from red to brick-brown.

Scatter the flour over the meat and vegetables and stir for 1 minute to cook out the raw flour taste.

Pour in the red wine and let it bubble for 3 minutes, scraping up any browned bits from the base of the pan.

Add the stock and Worcestershire sauce, stir to combine, then reduce the heat to low and simmer uncovered for 25–30 minutes, stirring occasionally, until the sauce is thick enough to coat the back of a spoon with no pooling liquid. Season generously with salt and black pepper. Transfer to a 28 × 20 cm baking dish if not already using one.

While the ragu simmers, drain the potatoes and place in a large pot. Cover with cold salted water and bring to a boil over high heat. Cook for 15–18 minutes until completely tender when pierced with a knife, then drain thoroughly and return to the pot over low heat for 1–2 minutes, shaking to steam-dry.

In a small saucepan over medium heat, melt the butter and continue cooking for 4–5 minutes, swirling often, until the milk solids turn golden-brown and smell nutty. Remove from heat immediately.

Pass the potatoes through a ricer or food mill back into the pot. Fold in the brown butter, warm milk, and egg yolks until smooth. Season with salt and white pepper.

Preheat the grill (broiler) to high. Spoon the mash over the ragu and spread in an even layer, then drag a fork across the surface to create ridges.

Place the dish under the grill 15 cm from the element and cook for 10–12 minutes until the peaks of the mash are deep golden brown and the filling is bubbling at the edges. Rest for 5 minutes before serving.