Preheat the oven to 375°F (190°C).
Heat olive oil in a large skillet over medium heat. Add diced onion and minced garlic, and sauté for 3-4 minutes until softened.
Add ground beef to the skillet. Cook, breaking it apart with a spoon, until browned and cooked through, about 6-8 minutes.
Season the beef mixture with salt, black pepper, paprika, dried thyme, and garlic powder. Stir well to combine. Remove from heat.
In a large bowl, combine beef broth and sour cream. Mix until smooth.
Lightly grease a 9×13 inch baking dish. Arrange half of the sliced potatoes in an even layer on the bottom of the dish.
Spread half of the cooked ground beef mixture evenly over the potatoes.
Pour half of the sour cream and beef broth mixture over the beef layer.
Sprinkle half of the shredded cheddar and mozzarella cheese evenly on top.
Repeat layering with the remaining potatoes, ground beef mixture, sour cream mixture, and cheeses.
Cover the casserole dish with aluminum foil and bake in the preheated oven for 35 minutes.
Remove the foil and bake for an additional 10 minutes, or until the cheese is melted and bubbly and the potatoes are tender when pierced with a fork.
Remove from oven and let the casserole rest for 5 minutes before serving.