clock clock iconcutlery cutlery iconflag flag iconfolder folder iconinstagram instagram iconpinterest pinterest iconfacebook facebook iconprint print iconsquares squares iconheart heart iconheart solid heart solid icon

Cheesy Onion Casserole Recipe

  • Author: Sweetpea
  • Prep Time: 20
  • Cook Time: 30
  • Total Time: 50 minutes
  • Yield: 8 1x
  • Category: side dish
  • Method: oven-baked
  • Cuisine: southern


Cheesy Onion Casserole is a side dish recipe idea that becomes the star of the show on any table! Onion lovers will enjoy the sweet onion flavor!


  • 3 lbs. Sweet Onions, sliced into 1/4‘1/2 inch half moons
  • 2 TBS Butter
  • 2 TBS Olive Oil
  • 4 cups Shredded Cheese
  • 1 cup Mayonnaise
  • 1 can Cream of Mushroom Soup
  • 1/2 can Milk
  • 1 tsp Parsley
  • 1 tsp Chives
  • 1/2 tsp Thyme
  • 1 tsp Garlic Powder
  • 1 tsp Onion Powder
  • 1/2 tsp Kosher Salt
  • 1/2 tsp Black Pepper


  1. Peel and slice your onions.
  2. In a large skillet, over medium heat, melt 2 tablespoons of butter and 2 tablespoons of olive oil.
  3. When the butter is foamy, add in your sliced onions, and stir.
  4. Cover and let soften for 10-15 minutes, stirring occasionally.
  5. In a large mixing bowl, add in your 4 cups of shredded cheese, 1 cup of mayonnaise, 1 can cream of mushroom soup, and 1/2 can of milk. Mix all of this together.
  6. Add in your one teaspoon of parsley, one teaspoons of chives, half a teaspoon of thyme, one teaspoon garlic powder, one teaspoon onion powder, half a teaspoon of kosher salt, and half a teaspoon of black pepper. Mix well.
  7. Once the onions are soft, pour them over the cheese and soup mixture — mixing to combine well.
  8. Pour into a buttered casserole dish (9×13 works great!), and bake at 350˚ for 30-35 minutes, on until the top is golden brown and bubbly.


You can use any shredded cheese you like, this recipe uses cheddar and mozzarella. But, it’s a great time to use up any leftover cheese in your fridge!

If you want to make this a few days before serving, cover with plastic wrap before baking, and store in the fridge. Allow the baking dish to come to room temperature before baking according to the directions.

Keywords: cheesy onion casserole

Recipe Card powered byTasty Recipes