Preheat your oven to 350°F. Heat olive oil in a large skillet over medium-high heat, then brown the ground beef for 5-7 minutes, breaking it apart as it cooks. Drain excess fat and set aside.
In the same skillet, sauté diced onion and minced garlic until fragrant, about 2-3 minutes. This aromatic base builds flavor for your casserole crowd favorite before adding other ingredients.
Stir in tomato paste and cook for 1 minute, coating the vegetables evenly. Add beef broth, diced tomatoes with juice, thyme, and oregano, mixing thoroughly to combine all flavors.
Return browned ground beef to the skillet and add uncooked egg noodles and sliced mushrooms. Simmer for 8-10 minutes until noodles are partially tender but still firm. The hearty ground beef casserole crowd recipe cooks further in the oven.
Remove from heat and stir in sour cream and half the shredded cheddar cheese until well combined. Season with salt and pepper to taste, adjusting for your preference.
Transfer the mixture to a greased 9x13 baking dish. Combine remaining cheddar cheese with breadcrumbs and melted butter, then sprinkle over the top evenly. This creates the signature crispy-cheesy topping.
Bake uncovered for 15-18 minutes until the topping turns golden brown and edges bubble gently. Let rest 3-5 minutes before serving for the cleanest portions.