Preheat the oven to 375°F (190°C).
Heat 1 tablespoon of olive oil in a large skillet over medium heat.
Add the diced onion and cook for 3 minutes until softened.
Add the diced green and red bell peppers to the skillet and cook for another 4 minutes until tender.
Add the ground beef to the skillet, breaking it apart with a spatula. Cook until browned and no longer pink, about 6-8 minutes.
Stir in garlic powder, smoked paprika, salt, and black pepper. Mix well.
Add the beef broth to the skillet, stir, and cook for 2 minutes until slightly reduced. Remove from heat.
In a large mixing bowl, combine the thawed diced potatoes O’Brien with 1 tablespoon olive oil and a pinch of salt and pepper. Toss to coat evenly.
Lightly grease a 9×13 inch casserole dish.
Spread half of the potatoes O’Brien evenly in the bottom of the casserole dish.
Layer the cooked ground beef and vegetable mixture evenly over the potatoes.
Top with the remaining potatoes O’Brien, spreading evenly.
Sprinkle the shredded cheddar and mozzarella cheeses evenly over the top layer.
Cover the casserole dish with aluminum foil and bake in the preheated oven for 30 minutes.
Remove the foil and bake for an additional 15 minutes until the cheese is melted and bubbly and the top is golden brown.
Remove from the oven and let the casserole rest for 5 minutes before serving.