Corned Beef Shepherd’s Pie with Cabbage

Place a large piece of corned beef into a saucepan with sliced onion and chopped celery, sprinkling the contents of the spice packet over the top. Pour in a sufficient amount of cold water to cover the ingredients, then turn the heat up high and bring the mixture to a boil. Remove any foam that forms on the surface, if desired. Once boiling, reduce the heat to a low simmer and cover the saucepan, allowing the corned beef to become tender after approximately 3.5 hours. Use a meat thermometer to check that the internal temperature has reached at least 145 degrees Fahrenheit (63 degrees Celsius).

Carefully lift the corned beef out of the saucepan and transfer it to a bowl, allowing it to cool. Taste the remaining broth and add salt if necessary.

Pour the cooled broth back into a saucepan, then bring it to a boil over high heat. Add shredded cabbage to the boiling broth and cook until it begins to soften and sweeten, taking around 5 minutes. Use a slotted spoon to remove the cabbage from the saucepan and transfer it to a separate bowl.

Add sliced carrots to the boiling broth, then cook until they start to soften, taking around 5 minutes. Use a slotted spoon to remove the carrots from the saucepan and transfer them to another bowl.

Add diced potatoes to the boiling broth, then reduce the heat to a medium simmer. Cook until the potatoes are tender, taking around 15-20 minutes.

While the potatoes are cooking, slice the cooled corned beef into thin strips along its fatty seam. Identify the direction of the meat fibers and cut across them (against the grain) to slice into 1/4-inch thick slices, discarding any large pieces of fat. Set the corned beef aside.

Preheat your oven to 400 degrees Fahrenheit (200 degrees Celsius). Butter a 9x15-inch casserole dish.

Use a slotted spoon to remove the cooked potatoes from the saucepan and transfer them to a separate bowl. Reserve the remaining broth. Add butter, salt, pepper, cayenne, and milk to the potatoes, then mix until they are very smooth. Stir in 3/4 cup of Cheddar cheese and combine until the cheese is fully incorporated.

Press the cabbage into a prepared casserole dish, then evenly distribute and press the carrots over the top. Place a layer of corned beef on top, overlapping it slightly and distributing the fatty pieces evenly until fully covered. Pour in 1 cup of the reserved broth, then dollop mashed potatoes over top and spread into a uniform layer using the back of a spatula. Drag the fork sideways across the potatoes to create a texture, repeating this process from top to bottom over the potatoes. Sprinkle with a little more Cheddar cheese.

Bake the casserole in the preheated oven until it is beautifully browned and piping hot, taking around 45-60 minutes.

Remove the casserole from the oven and let it rest for 10 minutes.

Meanwhile, warm any remaining broth over low-medium heat.

Cut the casserole into squares and garnish with chopped scallions. Serve the Shepherd's pie with warmed broth.