1. Prepare the Potato Layer

1. Bring a large pot of salted water to a boil. Add the diced potatoes and cook until tender, about 15 minutes.
2. Drain the potatoes and return them to the pot. Add butter, milk, mozzarella cheese, garlic powder, salt, and pepper. Mash until smooth and creamy. Set aside to cool slightly.

2. Cook the Beef Filling

1. Heat olive oil in a large skillet over medium heat. Add the chopped onion and sauté until softened, about 3-4 minutes.
2. Stir in the minced garlic and grated carrot, cooking for another 2 minutes.
3. Add the ground beef, breaking it apart with a spoon, and cook until browned.
4. Season with smoked paprika, cumin, oregano, salt, and pepper. Stir in the tomato paste and cook for 2-3 minutes, allowing the flavors to meld. Remove from heat and let cool.

3. Assemble the Roll

1. Preheat your oven to 375°F (190°C) and line a baking sheet with parchment paper.
2. Spread the mashed potatoes onto the parchment paper, forming an even rectangular layer about ½ inch thick.
3. Spread the beef filling evenly over the mashed potatoes, leaving a 1-inch border around the edges.
4. Using the parchment paper to assist, gently roll the potato layer from one short side to the other, creating a log. Seal the ends and smooth the surface.

4. Coat the Roll

1. Brush the roll with beaten egg to help the breadcrumbs adhere.
2. Sprinkle breadcrumbs evenly over the roll, pressing lightly to ensure they stick.

5. Bake the Roll

1. Transfer the roll to the prepared baking sheet. Bake for 25-30 minutes, or until the crust is golden and crispy.
2. Let the roll rest for 5 minutes before slicing into thick rounds.

6. Serve and Garnish

1. Garnish the slices with fresh parsley and serve hot with your choice of sauce.