In a large skillet, heat the olive oil over medium heat. Add the chopped onion and minced garlic, sautéing until fragrant and softened, about 3-4 minutes.
Add the ground beef to the skillet, breaking it apart with a spoon. Cook until browned and no longer pink, about 5-7 minutes. Season with salt, pepper, thyme, and paprika.
In a separate bowl, combine the beef broth and heavy cream. This will be the liquid for the casserole.
In a greased 9x13 inch baking dish, layer half of the sliced potatoes at the bottom. Season lightly with salt and pepper.
Spread the browned ground beef mixture evenly over the potatoes.
Pour half of the beef broth and cream mixture over the beef.
Layer the remaining potatoes on top, followed by the rest of the beef broth and cream mixture.
Finally, top with the shredded cheddar and mozzarella cheese.
Cover the dish with aluminum foil and bake in the preheated oven for 30 minutes. Then, remove the foil and bake for an additional 15-20 minutes until the cheese is bubbly and golden brown.
Remove from the oven and let it sit for about 10 minutes before serving to set.
Notes
Garnish with freshly chopped parsley for a pop of color and serve warm from the dish with a side of fresh salad for a complete meal.