Preheat the oven to 375°F (190°C). Grease a 9x13-inch baking dish with cooking spray or a little olive oil.

In a large pot, bring water to a boil. Add the diced sweet potatoes and cook for about 10-15 minutes, or until tender. Drain and set aside.

In a large skillet, heat the olive oil over medium heat. Add the diced onion and cook until translucent, about 3-4 minutes. Add the minced garlic and cook for an additional minute.

Add the ground beef to the skillet and cook until browned, breaking it apart with a spoon. Season with salt, black pepper, paprika, oregano, and thyme. Cook for another 5 minutes, stirring occasionally.

In a large bowl, combine the cooked sweet potatoes, cottage cheese, and milk. Mix until well combined.

In the prepared baking dish, layer half of the sweet potato mixture on the bottom. Top with the cooked ground beef mixture, then add the remaining sweet potato mixture on top. Sprinkle the shredded cheddar cheese evenly over the casserole.

Cover the baking dish with aluminum foil and bake for 25 minutes. Remove the foil and bake for an additional 10-15 minutes, or until the cheese is bubbly and golden.

Let the casserole cool for a few minutes before serving. Garnish with fresh parsley, if desired.