Preheat oven to 400ºF.

Cover the prunes with water and soak them for 20 minutes. Drain the prunes and roughly chop them. Set aside.

Heat the neutral oil in a wide pot over medium-high heat. Add the ground lamb and cook for 12–15 minutes until browned. Season with 1 teaspoon salt and ½ teaspoon black pepper. Transfer the cooked lamb to a paper towel-lined plate. Strain off all but 1 tablespoon of fat from the pot.

Turn the heat on the pot to medium. Add the yellow onions, carrots, and celery. Cook, stirring occasionally, for 6 to 8 minutes. Season with salt and pepper.

Add the tomato paste and minced garlic to the vegetables. Cook for 1 to 2 minutes, mashing the paste into the vegetables as it cooks.

Add the flour and toss to coat. Cook for 2 minutes more.

Pour in ½ cup red wine and turn the heat to medium-high, stirring to create a thick slurry. Add the Worcestershire sauce and 1½ cups beef stock. Whisk until a thick sauce forms.

Return the lamb to the pot along with the chopped prunes, thyme sprigs, and bay leaves.

Bring to a boil, taste, and season the gravy with salt and pepper. Reduce heat to low, cover, and simmer for 20 minutes. Stir occasionally and add a splash of water or beef stock if the liquid reduces too quickly.

Taste the gravy once more. Add the frozen peas and stir until incorporated. Turn off the heat and discard the bay leaves and thyme sprigs.

Add the potatoes to a large pot and cover with water. Add 2 teaspoons kosher and bring to a boil. Cook for 20 to 30 minutes until fork-tender. Drain the potatoes and set aside.

Send the potatoes through a ricer or food mill or mash them with a potato masher until free of lumps.

Add the softened butter, whole milk, and minced chives to the potatoes and mash until smooth and creamy. Taste and season with 1 teaspoon kosher salt and ½ teaspoon black pepper. Add more salt if desired.

Pour the gravy into a 9x13 baking dish. Spoon or pipe the mashed potatoes on top. I used a piping bag with a star tip and piped 2-inch dots across the baking dish. I filled in the gaps with smaller dots.

Transfer to the preheated oven for 30 minutes.

Turn on the broiler.

Broil until the potatoes turn golden brown on top, 2 to 3 minutes. Remove from the broiler and let stand for 10 minutes. Sprinkle with a pinch of freshly minced chives.

Spoon the shepherd’s pie onto plates. Enjoy!