Peel the sweet potatoes and potato, then cut them into large chunks. Boil or steam for 15–20 minutes until soft when pierced with a fork. Drain well.

Put the cooked potatoes in a bowl. Add milk, butter, salt, pepper, and a pinch of nutmeg. Mash or blend until smooth and creamy. Set aside.

Heat a large skillet over medium heat. Add the ground beef, salt, garlic powder, paprika, and chili flakes. Cook for 5–6 minutes, stirring occasionally, until the beef starts to brown.

Add the diced onion and red bell pepper to the skillet. Cook another 5–7 minutes until the beef is fully browned and the vegetables are soft.

Stir in the white miso until well mixed. Remove the skillet from heat.

Preheat your oven to 200°C (400°F).

Spread the beef mixture evenly in an ovenproof dish. Sprinkle a little mozzarella cheese over the beef.

Spread the mashed sweet potato mixture evenly on top of the beef layer. Sprinkle the remaining mozzarella cheese over the mashed potatoes.

Bake the casserole for 15–20 minutes, until the cheese is melted and golden brown.

Let it cool for a few minutes, then serve warm.