Creamy caramelized onions, cheese, and crispy cracker topping aka HEAVEN in a casserole. Onions are the star here!
- 2 pounds sweet onions, thinly sliced
- ½ stick butter
- 1 teaspoon kosher salt
- Black pepper
- ¼ cup mayonnaise
- ¼ cup sour cream
- ¼ cup grated parmesan cheese
- 2 ounces grated cheddar cheese (about 1 cup)
- 15 Ritz crackers (or similar), crushed
- Preheat a large skillet to low heat. Add the butter, onions, salt, and several grinds of pepper.
- Sauté the onions for 45-60 minutes, stirring every few minutes, until the onions are soft, translucent, and slightly golden. You may need to adjust the heat during this time depending on your stove; the onions should barely be sizzling and not browning, but should release liquid and cook down considerably.
- When the onions are soft, transfer to a large bowl. Prepare a 3-4 qt baking dish with cooking spray.
- Mix the onions with the mayo, sour cream, parmesan, and cheddar. Taste the mixture (YES YUM) and add more salt or pepper if you’d like.
- Scrape the onion mixture into the prepared baking dish and top with the crushed crackers.
- Bake at 375F for 30 minutes until bubbly and golden on top.
Any kind of parmesan you like will work well for this casserole. I prefer cheddar grated from a block for more melty/creaminess.
To avoid strange flavors/additives/sugars, I recommend regular, full fat sour cream, mayo, butter, and cheese. Any of them can be substituted with alternatives, but in general using original versions of ingredients like this will yield better flavor and texture.
Use any small-to-medium baking dish you like for this onion casserole! An 8x8 glass baking dish is the perfect size.
This dish can be made in advance and baked right before serving. Store it covered in the fridge for up to 4 days, then bake uncovered until hot and bubbly when you’re ready to eat. If the casserole is coming straight out of the fridge it might take a few extra minutes in the oven to heat all the way through.
- Prep Time: 20 minutes
- Cook Time: 90 minutes, mostly hands off
- Category: Side Dish
- Method: Bake
- Cuisine: American
Keywords: sweet onion casserole, thanksgiving casserole, thanksgiving side dish, onion casserole, vidalia onion casserole