Start by placing the quartered potatoes in a large pot. Cover them with cold water and sprinkle about a teaspoon of salt into it. Bring this to a boil over high heat.  Once boiling, reduce the heat to a simmer and cook until the potatoes are fork-tender, which usually takes about 15-20 minutes.

While your potatoes are cooking, heat the olive oil in a large skillet over medium heat. Add the chopped onion and sauté until it becomes translucent—this should take about 5 minutes. Add the ground beef, breaking it apart with a spoon.  Cook it until it’s browned, approximately 6-8 minutes. Drain any excess fat for a lighter dish.

Once your meat is brown, stir in the beef stock and Worcestershire sauce. Season with freshly ground black pepper and sea salt to taste. Toss in your mixed frozen veggies and allow everything to simmer on low for around 5 minutes. Set this flavorful mixture aside.

After your potatoes have cooked, drain them and return them to the pot. Add 6 tablespoons of butter along with a pinch of sea salt. Mash the potatoes until smooth. If you like, you can stir in a splash of milk for extra creaminess.

Preheat your oven to 400°F (200°C). In a baking dish, pour the beef and veggie mixture. Spread it out evenly. Top it with the mashed potatoes, spreading them out with a spatula to create a smooth layer. Then, sprinkle the grated cheddar cheese on top for that irresistible, bubbly finish.

Place your baking dish in the preheated oven. Bake for around 25 minutes or until golden and bubbling. Your kitchen will soon be filled with an enticing aroma that beckons everyone to the table.

Once done, take it out and let it cool for a few minutes. This way, the flavors can settle, and you can avoid a burning tongue!