Preheat your oven to 375°F. Peel the potatoes and dice them into small, uniform cubes about ½-inch in size. Chop the onion and mince the garlic cloves, setting them aside together.

Heat the olive oil in a large skillet over medium heat. Add the chopped onion and minced garlic, cooking for about 2-3 minutes until they become fragrant and softened. The onion should turn translucent.

Add the ground beef to the skillet, breaking it up with your spoon as it cooks. Season with salt, black pepper, thyme, and paprika. Continue cooking for 6-8 minutes until the beef is completely browned with no pink remaining. Drain excess grease if needed.

Pour in the beef broth and stir everything together, allowing the mixture to simmer for 2-3 minutes so the flavors can blend. Remove the skillet from the heat.

In a large mixing bowl, combine the diced potatoes with the cooked beef mixture. Fold in the sour cream and half of the shredded cheddar cheese, stirring until everything is well incorporated.

Transfer the beef and potato mixture into a 9x13-inch baking dish, spreading it out in an even layer. Sprinkle the remaining cheddar cheese evenly across the top.

Cover the dish tightly with aluminum foil and bake for 30 minutes. Then remove the foil and continue baking for another 10-15 minutes, until the cheese topping is melted, bubbling, and beginning to turn golden.

Let the casserole rest for 10 minutes before serving. This resting time allows the layers to set properly, makes serving much easier, and ensures the potatoes are fork-tender throughout.