My sister refuses to host a family dinner unless I bring a double batch of this. You only need 3 ingredients to make it.

This southern 3-ingredient sweet onion dip is the one dish my family will not let me show up without. My sister literally refuses to host a family dinner unless I promise to bring a double batch, and honestly, I don’t blame her. It’s based on those classic church potluck onion bakes you see all over the South—simple pantry staples, no fancy steps, and it comes out of the oven bubbling, golden, and impossible to stop eating. If you can slice an onion and turn on the oven, you can make this, even on a busy weeknight before heading to a get-together.

Serve this dip straight from the oven while it’s still hot and bubbly, with sturdy dippers like thick-cut potato chips, buttery crackers, or toasted baguette slices so they can handle the gooey cheese. It’s also great with baby carrots, celery sticks, and bell pepper strips if you want something a little lighter on the table. I like to park the glass casserole dish in the center of the coffee table on a trivet and surround it with bowls of different chips and veggies so everyone can crowd around and dig in family-style.

Servings: 8

2 cups finely chopped sweet onion (such as Vidalia, about 1 large onion)

Preheat your oven to 350°F (175°C). Grab a small glass casserole dish or baking dish, about 8x8 inches or similar size. There’s no need to grease it—the mayo and cheese have enough fat to keep things from sticking.

Peel the sweet onion and finely chop it. You want small pieces so the onion softens and practically melts into the dip as it bakes, instead of staying crunchy. Measure out 2 cups of chopped onion and add it to a medium mixing bowl.

Add the shredded Swiss cheese and mayonnaise to the bowl with the onions. Stir everything together until the onions are evenly coated and there are no streaks of plain mayo. The mixture will be thick and chunky, almost like a cheesy onion salad.

Transfer the onion mixture to your glass casserole dish. Use a spatula to spread it into an even layer all the way to the edges so it bakes uniformly. Smooth the top a bit so it browns evenly in the oven.

Bake, uncovered, on the middle rack for 25–30 minutes, or until the top is bubbly and a deep golden brown around the edges. If your oven runs hot, start checking at 20 minutes. The onions should be tender and the center should look melted and creamy.

Carefully remove the dish from the oven and let the dip sit for about 5–10 minutes. This short rest helps it set up just enough so it’s scoopable but still gooey in the center, with that bubbly, browned crust on top.

Serve the dip right in the glass casserole dish while it’s warm, with your favorite dippers arranged around it. Stir gently from the edges toward the center as you scoop so everyone gets a mix of the caramelized top and creamy middle. Refrigerate any leftovers in the same dish, covered, and reheat in the oven until hot and bubbly again.

To keep the spirit of the 3-ingredient recipe, I like to treat any extras as totally optional, but there are a few fun ways to switch things up. For a slightly milder flavor, swap half of the Swiss cheese for shredded mozzarella or Monterey Jack; for a sharper, more robust bite, use Gruyère in place of Swiss. If you want a touch of color and heat, sprinkle a pinch of paprika or red pepper flakes over the top before baking. You can also prep this ahead: stir everything together, spread it in the glass casserole dish, cover, and refrigerate up to 24 hours, then bake just before serving (add 5–10 minutes to the bake time if it goes in the oven cold). If you’re cooking for a smaller group, halve the recipe and use a smaller baking dish; for my sister’s big family dinners, I double it and bake in a 9x13-inch glass casserole so there’s plenty of that golden brown crust for everyone. For easier cleanup on a hectic day, line the bottom of the dish with a piece of parchment cut to fit—just know the edges may not brown quite as deeply, so I usually skip this when I want that extra toasty top.