Cheesy Onion Casserole Recipe

Introduction

This Cheesy Onion Casserole is a comforting and flavorful dish perfect for family dinners or potlucks. Sweet onions blend beautifully with creamy cheese and savory herbs, baked until golden and bubbly. It’s an easy side that everyone will love.

Ingredients

• 3 lbs. sweet onions, sliced into 1/4 to 1/2 inch half moons
• 2 tablespoons butter
• 2 tablespoons olive oil
• 4 cups shredded cheese
• 1 cup mayonnaise
• 1 can cream of mushroom soup
• 1/2 can milk
• 1 teaspoon parsley
• 1 teaspoon chives
• 1/2 teaspoon thyme
• 1 teaspoon garlic powder
• 1 teaspoon onion powder
• 1/2 teaspoon kosher salt
• 1/2 teaspoon black pepper

Instructions

1. Step 1: Peel and slice your onions into half moons about 1/4 to 1/2 inch thick.
2. Step 2: In a large skillet over medium heat, melt the butter with the olive oil until the butter is foamy.
3. Step 3: Add the sliced onions to the skillet and stir to coat with the butter and oil.
4. Step 4: Cover the skillet and let the onions soften for 10 to 15 minutes, stirring occasionally to prevent browning.
5. Step 5: While the onions soften, combine the shredded cheese, mayonnaise, cream of mushroom soup, and milk in a large mixing bowl. Mix thoroughly.
6. Step 6: Add parsley, chives, thyme, garlic powder, onion powder, kosher salt, and black pepper to the cheese mixture. Stir until well combined.
7. Step 7: Once the onions are soft, pour them into the cheese and soup mixture and stir to combine everything evenly.
8. Step 8: Transfer the mixture to a buttered 9×13 inch casserole dish and bake at 350°F (175°C) for 30 to 35 minutes, until the top is golden brown and bubbly.

Tips & Variations

• Use sharp cheddar or a blend of cheeses for extra flavor and meltiness.
• For a vegetarian version, ensure the cream of mushroom soup is vegetarian-friendly or use a homemade mushroom sauce.
• Add crispy cooked bacon or caramelized onions on top before baking for added texture and flavor.
• If you prefer a lighter casserole, substitute half the mayonnaise with Greek yogurt.

Storage

Store leftovers in an airtight container in the refrigerator for up to 3 days. To reheat, warm the casserole in a preheated 350°F (175°C) oven until heated through and bubbly, or microwave individual portions until hot.

How to Serve

Serve this delicious recipe with your favorite sides.

FAQs

Can I use other types of onions?

Yes, you can use yellow or Vidalia onions if you prefer a milder or sharper flavor. Sweet onions work best for their natural sweetness that balances the cheese.

Can I prepare this casserole ahead of time?

Absolutely! You can assemble the casserole up to a day in advance, cover it tightly, and refrigerate it. When ready, bake it from cold, adding a few extra minutes to the baking time.

Cheesy Onion Casserole Recipe

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5 from 73 reviews

This Cheesy Onion Casserole is a rich and comforting dish featuring sweet onions softened in butter and olive oil, combined with a creamy blend of cheese, mayonnaise, and mushroom soup, then baked to golden perfection. Perfect as a savory side or a hearty addition to any meal.

• Author: nova
• Prep Time: 20 minutes
• Cook Time: 35 minutes
• Total Time: 55 minutes
• Yield: 8 servings 1x
• Category: Casserole
• Method: Baking
• Cuisine: American

Ingredients

Scale 1x2x3x

Onions and Fat

• 3 lbs. Sweet Onions, sliced into 1/4 to 1/2 inch half moons
• 2 tablespoons Butter
• 2 tablespoons Olive Oil

Cheese Mixture

• 4 cups Shredded Cheese (cheddar or a blend works well)
• 1 cup Mayonnaise
• 1 can Cream of Mushroom Soup (approx. 10.5 oz)
• 1/2 can Milk (use the same soup can for measurement)

Seasonings

• 1 teaspoon Parsley
• 1 teaspoon Chives
• 1/2 teaspoon Thyme
• 1 teaspoon Garlic Powder
• 1 teaspoon Onion Powder
• 1/2 teaspoon Kosher Salt
• 1/2 teaspoon Black Pepper

Instructions

1. Prepare Onions: Peel and slice your sweet onions into 1/4 to 1/2 inch half moons, ensuring even thickness for uniform cooking.
2. Heat Fat: In a large skillet over medium heat, melt 2 tablespoons of butter and 2 tablespoons of olive oil together until the butter becomes foamy.
3. Cook Onions: Add the sliced onions to the skillet and stir to coat them evenly in the butter and oil mixture.
4. Soften Onions: Cover the skillet and let the onions soften over medium heat for 10 to 15 minutes, stirring occasionally to prevent sticking or burning.
5. Mix Cheese Base: In a large mixing bowl, combine 4 cups shredded cheese, 1 cup mayonnaise, 1 can of cream of mushroom soup, and half a can of milk. Stir thoroughly to create a creamy mixture.
6. Add Seasonings: Incorporate 1 teaspoon parsley, 1 teaspoon chives, 1/2 teaspoon thyme, 1 teaspoon garlic powder, 1 teaspoon onion powder, 1/2 teaspoon kosher salt, and 1/2 teaspoon black pepper into the cheese mixture. Mix well to evenly distribute the flavors.
7. Combine Onions and Cheese Mixture: Once the onions are soft and fragrant, pour them into the cheese and soup mixture. Stir until all ingredients are thoroughly combined.
8. Prepare and Bake: Butter a 9×13-inch casserole dish and pour in the combined mixture, spreading it evenly. Bake in a preheated oven at 350°F (175°C) for 30 to 35 minutes, or until the top is golden brown and bubbly. Allow to cool slightly before serving.

Notes

• For best results, use sweet onions such as Vidalia or Walla Walla for a naturally sweeter flavor.
• You can substitute the cream of mushroom soup with cream of chicken or celery soup if preferred.
• Feel free to use a blend of cheeses like cheddar and Monterey Jack for added flavor complexity.
• This casserole can be prepared ahead of time and refrigerated before baking; increase baking time slightly if baking from cold.
• Leftovers can be stored covered in the refrigerator for up to 3 days and reheated in the oven for best texture.

Keywords: Cheesy Onion Casserole, onion casserole, baked onion dish, cheesy side dish, comfort food casserole