In a large skillet, heat the olive oil over medium heat. Add the diced onion and garlic, sautéing until the onion softens (about 3-4 minutes).
Add the ground beef to the skillet, breaking it apart with a spatula. Cook until browned and cooked through, about 5-7 minutes. Drain any excess fat.
Mix in the diced bell peppers, sauté for another 2-3 minutes until they start to soften.
Stir in the chopped spinach, diced tomatoes, Worcestershire sauce, paprika, oregano, salt, and pepper. Cook for an additional 2 minutes until the spinach wilts.
In a greased 9x13-inch baking dish, layer half of the sliced potatoes on the bottom. Pour half of the beef mixture over the potatoes.
Repeat the layers with the remaining potatoes and beef mixture.
Cover the dish with aluminum foil and bake in the preheated oven for 30 minutes.
Remove the foil and sprinkle the shredded cheddar cheese over the top. Return to the oven and bake uncovered for an additional 15 minutes, or until the cheese is bubbly and golden.
Allow the casserole to cool for a few minutes before slicing and serving.
Notes
Serve each portion on a plate, garnished with fresh parsley or a dollop of sour cream for an extra flair.