Using a knife or mandolin, cut the potatoes into slices 1/8-inch (3 mm) thick.
On a parchment-lined baking sheet, sprinkle half of the Parmesan and spread it evenly over the parchment.
Place the potatoes over the parmesan so each slice overlaps the previous one both vertically and horizontally, until the pan is filled.
Sprinkle the rest of the Parmesan evenly over the potatoes and season with 1 teaspoon salt.
Bake 30 minutes, until golden and the potatoes are flexible and slightly crispy.
In a skillet, heat 2 tablespoons olive oil over medium. Once shimmering, add the onions and cook until caramelized, about 15 minutes.
Add the beef, breaking it up and mixing with the onion until cooked. Stir in the tomatoes, 3 tablespoons parsley, paprika, 1 teaspoon salt, and pepper. Cook until browned and cooked through, then remove from heat.
In another skillet, heat 2 tablespoons olive oil over medium. Add the spinach and cook until wilted. Add 1 teaspoon salt and the garlic, stir to combine, and remove from heat.
In a bowl, combine the spinach mixture with the ricotta.
Evenly spread the spinach-ricotta mixture over the cooked potato sheet.
Evenly spread the beef mixture over the spinach, then sprinkle mozzarella over the beef.
Take one end of the potato sheet, holding the parchment, and roll upward, keeping the filling from coming out the ends.
Once rolled, place the potato roll on the parchment and bake 15 minutes.
Sprinkle with parsley to garnish. Slice and serve immediately.
