Flag Day Ground Beef Casserole with Creamy Mushroom Topping

This 4-ingredient ground beef casserole is the kind of easy comfort food that makes busy evenings feel effortless. With just ground beef, condensed cream of mushroom soup, sour cream, and Italian seasoning, you can create a rich, creamy oven-baked beef casserole with very little prep.

It’s an especially easy choice for a Flag Day dinner, summer gathering, family potluck, or simple weeknight meal. The beef creates a hearty savory base while the creamy mushroom and sour cream topping bakes into a thick, comforting layer with plenty of herb flavor.

Best of all, there’s no complicated assembly. Brown the beef, stir together the creamy topping, layer everything in a casserole dish, and let the oven finish the job.

Why You’ll Love This 4-Ingredient Casserole

• Only 4 simple ingredients – Great when you want dinner without a long grocery list.
• Easy weeknight dinner – Minimal preparation makes this ideal for busy evenings.
• Budget-friendly – Ground beef and canned soup create a filling meal without expensive ingredients.
• One-dish comfort food – Everything finishes baking together in one casserole dish.
• Family-friendly flavor – Creamy, savory, and mild enough for most picky eaters.
• Perfect for potlucks – The casserole is easy to portion and serve warm.
• Make-ahead friendly – Prepare components ahead of time and bake when needed.
• Customizable – Change the herbs or use ground turkey for a lighter variation.

Servings: 6
Prep Time: 10 minutes
Cook Time: 30–35 minutes
Resting Time: 10–15 minutes
Total Time: About 55–60 minutes
Oven Temperature: 350°F (175°C)

Ingredients

• 1 1/2 pounds ground beef, 80–90% lean
• 2 cans (10.5 ounces each) condensed cream of mushroom soup
• 1 cup sour cream
• 1 teaspoon dried Italian seasoning

How to Make This Easy Ground Beef Casserole

1. Preheat the oven.
Preheat your oven to 350°F (175°C). Set a 9×13-inch glass casserole dish aside. There is generally no need to grease it because the cooked beef provides enough fat to prevent sticking.

2. Brown the ground beef.
Place the ground beef in a large skillet over medium heat. Break it apart with a spoon and cook for about 7–10 minutes, or until fully browned with no pink remaining. If there is excess grease, carefully drain most of it.

3. Add the beef to the casserole dish.
Transfer the cooked ground beef to the casserole dish and spread it into an even layer.

4. Make the creamy topping.
In a bowl, combine the condensed cream of mushroom soup and sour cream. Stir until mostly smooth, then mix in the dried Italian seasoning.

5. Layer the casserole.
Spoon the creamy mushroom mixture evenly over the cooked ground beef. Spread it gently toward the edges so the entire beef layer is covered.

6. Bake.
Place the uncovered casserole on the middle oven rack. Bake for 30–35 minutes, until the edges are bubbling and the creamy topping looks set and glossy.

7. Let it rest.
Remove the casserole from the oven and allow it to rest for 10–15 minutes. This gives the creamy layer time to firm slightly while keeping the casserole rich and spoonable.

8. Serve warm.
Scoop the casserole onto plates or into bowls, making sure every serving gets both the savory beef and creamy mushroom topping.

What to Serve with Ground Beef Casserole

Turn this easy casserole into a complete family dinner by serving it with simple sides such as:

• Steamed green beans
• Buttered mixed vegetables
• Fresh green salad
• Corn on the cob
• Creamy coleslaw
• Sliced summer tomatoes
• Dinner rolls
• Garlic bread
• Buttered toast
• Fresh fruit salad
• Watermelon

For a Flag Day or summer dinner, watermelon, corn, tomatoes, and crisp coleslaw make especially easy side dishes.

Easy Variations

Use ground turkey: Substitute lean ground turkey for the beef if you prefer a lighter casserole.

Change the herbs: Use dried parsley and oregano instead of Italian seasoning for a milder flavor.

Try another condensed soup: Cream of chicken or cream of celery can replace one can of cream of mushroom soup for a slightly different flavor.

Add vegetables: Cooked mushrooms, onions, peas, or other favorite vegetables can be added when you aren’t following the strict 4-ingredient version.

Make it gluten-free: Choose gluten-free condensed soup and verify that your seasoning blend is gluten-free.

Add a little color: A light sprinkle of smoked paprika over the creamy topping can give the casserole an attractive reddish finish.

Recipe Tips

• Drain excess grease from the beef so the casserole doesn’t become oily.
• Spread the creamy topping evenly for consistent flavor in every serving.
• Don’t skip the 10–15 minute resting period; it helps the casserole set.
• For food safety, cook ground beef to at least 160°F (71°C).
• Refrigerate leftovers within 2 hours.
• Store leftovers covered in the refrigerator and use within 3–4 days.
• Reheat leftovers until steaming hot throughout.
• If using low-fat sour cream, avoid broiling or aggressively boiling the topping because it can separate.

Storage and Reheating

Store leftover ground beef casserole in a covered container in the refrigerator for up to 3–4 days. Reheat individual portions in the microwave or reheat a larger amount in the oven until heated completely through.