Preheat the oven to 400°F (200°C). Lightly grease a 9×13-inch baking dish and a large baking sheet.
In a large bowl, toss diced potatoes with olive oil, ½ teaspoon salt, and ¼ teaspoon black pepper. Spread evenly on the baking sheet and roast for 20–25 minutes until golden and crisp.
While the potatoes roast, brown the ground beef in a skillet over medium-high heat. Drain excess fat.
Add chopped onion to the beef and cook for 5–7 minutes until soft. Stir in garlic, paprika, and remaining salt and pepper. Cook for 1 minute until fragrant.
Transfer roasted potatoes into the prepared baking dish. Spread the cooked beef mixture evenly on top.
Sprinkle both cheddar and Monterey Jack cheese evenly over the top.
Bake uncovered for 15–20 minutes, until cheese is melted, bubbly, and lightly golden.
Remove from oven, cool for a few minutes, garnish with chopped parsley, and serve warm.
