Save The first time I made this, I was standing at my stove on a Tuesday evening, listening to oil crackle while onions turned golden in the pan. My roommate wandered into the kitchen asking what smelled so good, and I realized I'd accidentally stumbled onto something special—crispy onions between melted cheese and buttered bread felt like the kind of thing that shouldn't work but absolutely does. That moment of discovery became my favorite reason to make it again and again.
I’ve been getting a lot of questions about the pot I use for cozy one-pot meals and small-batch recipes, so I wanted to quickly share it here.
This is the Martha Stewart heart-shaped enameled cast iron Dutch oven (2-quart). It’s one of those pieces I reach for constantly when testing soups, stews, baked casseroles, and smaller comfort-food recipes.
- Heats evenly with no hot spots (huge for slow cooking)
- Non-reactive enamel interior — no seasoning required
- Perfect size for small households or side dishes
- Sturdy handles, easy to move from oven to table
It’s also a favorite with home cooks — 4.6 out of 5 stars from over 1,900 reviews — and Amazon often has a coupon available, depending on color and size.
👉 Check current price, colors, and coupon on Amazon
(Affiliate link — if you choose to buy, it helps support this recipe blog at no extra cost to you ❤️)
I made these for my sister during a snowstorm when we were snowed in, and we ended up eating them with tomato soup while watching the snow pile up outside the window. We didn't talk much, just ate and kept warm, and somehow that simple meal meant more than any fancy dinner ever could.
Ingredients
- Yellow onion: Thinly sliced so they fry up into delicate, lacy crisps—this is where the magic happens.
- All-purpose flour and cornstarch: Together they create a coating that's crispy outside and holds up to the frying without getting greasy.
- Paprika, salt, and pepper: These season the coating itself, so every crispy piece tastes like intentional flavor, not just fried dough.
- Buttermilk: The acid helps the coating adhere and adds a subtle tangy note that keeps things interesting.
- Vegetable oil: Use something neutral so the onion flavor stays front and center—not coconut or olive for this one.
- Sourdough or white bread: Sourdough gives you character and tang, but white bread is comforting if that's what you're craving.
- Sharp cheddar and mozzarella: The cheddar brings sharpness and complexity while the mozzarella does the heavy lifting for melt and stretch.
- Unsalted butter: Softened so it spreads easily and browns evenly in the pan, giving you that golden crust everyone wants.
Instructions
- Mix Your Coating:
- Whisk flour, cornstarch, salt, pepper, and paprika together in a shallow bowl until everything is evenly distributed. Pour buttermilk into another bowl so you have a dipping station ready to go.
- Fry the Onions:
- Heat about an inch of oil in your skillet until it shimmers and moves easily around the pan, then working in batches so you don't crowd the pan, dip each onion slice in buttermilk and drag it through the flour mixture. Watch them turn golden and crispy—usually two to three minutes does it—then pull them out onto paper towels where they'll continue to crisp up as they cool.
- Butter Your Bread:
- Spread softened butter on one side of each bread slice, making sure you get into the corners so everything browns evenly.
- Build the Sandwich:
- Place two slices buttered side down on your work surface, then sprinkle half your cheddar and mozzarella blend over each one. Layer your crispy onions generously on top—don't be shy here—then finish with the remaining cheese and your second bread slice, buttered side up.
- Cook Until Golden:
- Set your skillet or griddle to medium-low and let it warm up, then lay your sandwiches down gently and give them about three to four minutes on each side. Press down softly as they cook so the cheese gets cozy with the bread, and you'll know they're ready when the bread is deep golden and you can hear the cheese bubbling slightly at the edges.
- Rest and Serve:
- Lift them out onto a cutting board and let them sit for just a minute so the cheese sets slightly, then cut them in half and serve while everything is still hot.
Save One weekend I made these for my neighbor who'd been dealing with a rough week, and watching her face light up when she bit into one reminded me that food is really just an excuse to show someone you're thinking of them. That sandwich became the start of a friendship I didn't expect.
The Onion Question
Some people ask me why I'd make crispy onions from scratch when you can buy them in a can, and honestly, if you're short on time or energy, store-bought absolutely works and saves you the frying step. But there's something about slicing your own onion paper-thin and watching it transform that feels a little ceremonial—like you're taking an extra minute to care about what you're eating. The flavor is fresher too, with a delicate sweetness that canned onions can't quite capture.
Playing with Flavor
I've experimented with adding a thin swipe of Dijon mustard under the cheese layer, and it brings this sharp, almost peppery note that plays beautifully against the sweet onions. Tomato slices work too if you want to add freshness, though I drain them first so they don't make the bread soggy. Once I even added a tiny pinch of smoked paprika to the coating and couldn't believe how much deeper the flavor became.
What This Pairs With
This sandwich is happiness beside a bowl of tomato soup, or next to a simple green salad if you want something lighter. I've also made it work with roasted vegetable sides or even a pickle spear on the side for brightness. There's something about having one element that's warm and comforting and one that's crisp and fresh that makes the whole meal feel balanced and complete.
- A cup of hot tomato soup turns this into a nostalgic dinner that feels like home.
- Serve it with crispy pickles or a light vinegar-based slaw for contrast.
- Don't skip letting the sandwich rest for a minute—that brief pause before eating changes everything.
Save This sandwich reminds me that sometimes the best meals come from playful experiments and small moments of connection in the kitchen. Make it and see what memories it creates for you.
Recipe FAQ
- → How do I achieve crispy fried onions?
Thinly slice onions, dip them in buttermilk, then dredge in a seasoned flour and cornstarch mix. Fry in hot oil until golden and crunchy. Drain on paper towels before using.
- → Which cheeses work best for this sandwich?
Sharp cheddar and mozzarella offer a mix of bold flavor and creamy melt, making them ideal for this sandwich’s gooey texture.
- → What bread types are recommended?
Sourdough or white bread hold up well to cooking and provide a nice toasty texture without overpowering the fillings.
- → Can this be prepared ahead of time?
Fry the onions in advance and assemble sandwiches just before cooking to maintain their crispness and cheese melt.
- → What cooking method ensures even melting and toast?
Cook sandwiches over medium-low heat in a nonstick skillet or griddle, pressing gently for 3–4 minutes per side until golden brown.