These southern 3-ingredient cheesy onion squares are the sort of simple, homespun party food that disappears faster than just about anything else on the table. They remind me of the kind of buttery, oniony bakes that have long shown up at church suppers, card parties, and football gatherings across the South and Midwest alike, where a short ingredient list and a hot oven could still turn out something mighty comforting. When you need a recipe that feels generous without asking much of you, this one earns its place.
Serve these squares warm as an appetizer, snack, or easy side for chili, pulled pork sandwiches, burgers, grilled chicken, or a pot of beans. They also fit right in on a game-day spread with pickles, celery sticks, little smokies, and a cold glass of sweet tea or lemonade, and they are rich enough that a crisp green salad on the side makes a fine balance.
Southern 3-Ingredient Cheesy Onion Squares
Servings: 12 squares
Ingredients
2 cups sweet onions, finely chopped
2 cups mayonnaise
2 cups shredded sharp cheddar cheese
Directions
1. Preheat the oven to 350°F. Line a baking tray or small baking pan with foil for easy cleanup.
2. In a large bowl, stir together the finely chopped onions, mayonnaise, and shredded cheddar cheese until everything is evenly combined.
3. Spread the mixture evenly onto the foil-lined tray or pan, pressing it into an even layer so it bakes up neatly.
4. Bake for 25 to 30 minutes, or until the top is deeply golden, the edges are crisp and caramelized, and the cheese is bubbly.
5. Let the bake cool for several minutes, then cut into squares and serve warm.
Variations & Tips
Sharper Cheese: If you want a bolder bite, use extra-sharp cheddar instead of regular sharp cheddar. It gives these little squares a deeper, tangier flavor that stands up especially well on a snack table.
Onion Choice: Sweet onions are my favorite here because they bake up mellow and tender, but yellow onions will work too. If using a stronger onion, chop it fine so it softens well and blends into the filling.
Cleaner Slices: For tidy squares, let the pan rest 10 to 15 minutes before cutting. That little bit of patience helps the cheese set and keeps the pieces from scooping out too loosely.
Party Pan Tip: This recipe can easily be doubled for a crowd and baked in a larger pan. Just keep an eye on the color along the edges, since that is where you will first see those good crispy bits that tell you it is ready.
Make-Ahead Help: You can mix the onions, mayonnaise, and cheese a few hours ahead and keep it covered in the refrigerator until baking time. Then spread it in the pan and bake just before serving so it comes out hot and bubbling.