20-Minute Keto Big Mac Smash Burger
This keto Big Mac smash burger delivers all the fast-food flavor you crave without the carb overload. Thin, crispy beef patties pile high with tangy special sauce, melted cheese, and classic fixings on a soft low-carb bun.
It’s a weeknight dinner that feels like a drive-thru indulgence, but comes together in about 20 minutes with just a few simple ingredients.
Why This Keto Burger Works
The smash method creates lacy, deeply browned edges on the patties, giving you that signature crust without a grill. A quick homemade sauce tastes shockingly close to the original, and stirring it together takes longer to describe than to do.
Using keto-friendly buns means you still get the full two-handed burger experience, no lettuce wrap required unless you want one. The whole thing is fast enough for a Tuesday but satisfying enough to kill any burger craving.
Ingredients
- 1 lb ground beef (80/20): The higher fat content keeps the smashed patties juicy and helps them develop that crisp crust.
- ½ tsp salt, plus more to taste: Season the patties right after smashing for the best flavor.
- ¼ tsp black pepper: Freshly ground if you have it.
- 4 slices American cheese: This is the classic choice; use a keto-friendly brand with zero or very low carbs.
- 2 keto burger buns: Store-bought or homemade, look for ones with 5g net carbs or fewer per bun.
- ½ cup shredded iceberg lettuce: Crisp, cold lettuce gives the right texture and a little freshness.
- 8 dill pickle slices: The bright acidity cuts through all the richness.
- 2 tbsp finely diced white onion: A tiny bit goes a long way for that familiar Big Mac bite.
- ¼ cup mayonnaise: Full-fat mayo is the base of the sauce and works best for keto.
- 2 tbsp sugar-free ketchup: Check labels for one with no added sugar.
- 1 tbsp yellow mustard: Plain American yellow mustard, nothing fancy.
- 2 tbsp dill pickle relish (sugar-free): If you can’t find sugar-free relish, chop 1 small dill pickle very fine instead.
- 1 tsp white vinegar: A little acid wakes up all the flavors.
- ½ tsp paprika: Sweet paprika; smoked works in a pinch.
- ½ tsp onion powder
- ½ tsp garlic powder
Variations / Substitutions
- Lettuce wrap: Swap the keto buns for 4 large romaine or iceberg lettuce leaves, using them as cups or wraps.
- Cheese: Cheddar, provolone, or pepper jack all melt well and change the character just enough to keep things interesting.
- No onion: Omit the diced onion entirely or use a tiny pinch of onion powder in the sauce instead.
- Spicy version: Add a few shakes of hot sauce to the special sauce or a pinch of cayenne to the beef.
If you enjoy this, you might also like our Keto Bacon Cheeseburger Casserole for another easy low-carb dinner.
How to Make Keto Big Mac Smash Burger
Step 1: Mix the Sauce
In a small bowl, whisk together the ¼ cup mayonnaise, 2 tbsp sugar-free ketchup, 1 tbsp yellow mustard, 2 tbsp dill pickle relish, 1 tsp white vinegar, ½ tsp paprika, ½ tsp onion powder, and ½ tsp garlic powder until smooth. Taste and add a pinch of salt if needed.
The sauce will look pale and a little lumpy from the relish, which is exactly right. Set it aside on the counter while you cook the patties so the flavors have a few minutes to blend.
Step 2: Smash and Sear the Patties
Heat a large cast-iron skillet over high heat until it’s smoking. While it heats, divide the 1 lb ground beef into 4 equal portions and roll each into a loose ball.
Carefully place 2 balls in the hot skillet, then immediately use a sturdy metal spatula and a small square of parchment paper to press each one down as flat as it will go. Season the tops with ½ tsp salt and ¼ tsp black pepper, divided between them. Cook without moving for 2 minutes, until the edges look dark brown and crisp. Flip each patty, lay a slice of American cheese on top, and cook for another 1 minute. Transfer the patties to a plate and repeat with the remaining 2 balls.
Step 3: Build the Burgers
Spread a generous spoonful of sauce on the cut sides of both keto buns. On the bottom bun, layer half of the shredded lettuce, 4 pickle slices, and 1 tablespoon diced onion. Stack two cheeseburger patties on top, then close with the top bun.
Serve right away while the cheese is gooey and the patties are hot enough that the cold lettuce stays crisp. A few paper napkins won’t hurt.
A Few Notes for the Best Keto Smash Burger
- Use beef with at least 20% fat. Lean ground beef won’t render enough fat to create those crispy, lacy edges, and the patties will end up dry.
- A cast-iron skillet holds heat better than any nonstick pan and gives you the deepest sear. If you don’t have one, the heaviest skillet you own is your next best bet.
- Smash once with firm pressure and don’t wiggle the spatula. You want the meat to stick and develop a crust, not shift around.
- The sauce can be made up to 5 days ahead and stored in the fridge. It thickens a little as it sits, so let it come to room temperature while you cook.
Storing Leftover Burgers
- Refrigerate: Store the cooked patties, sauce, and fixings separately. The patties keep for up to 3 days in an airtight container.
- Reheating: Warm the patties in a dry skillet over medium heat for about a minute per side. This crisps up the edges again without drying them out. A microwave will steam them and ruin the crust.
- Serve cold: Cold smash patties with plenty of sauce make a surprisingly good snack, though the cheese won’t be melty.
What to Serve With Keto Big Mac Smash Burger
A simple side salad with a sharp vinaigrette cuts through the richness in a way that fries never could. Roasted broccoli or asparagus tossed in olive oil and salt also works well, providing a warm, charred element that feels like a diner plate without the carbs.
Frequently Asked Questions
Can I use a different ground meat?
Yes. Ground turkey or chicken will work, but choose one with a higher fat content (at least 90/10 is labeled, but 85/15 or 93/7 won’t crisp the same way). The texture will be softer and less beefy.
Do I have to use a cast-iron skillet?
No, but it’s the best tool for the job. Any heavy skillet that can handle high heat will work. Avoid thin nonstick pans, which can warp and won’t give you much browning.
Can I skip the bun entirely?
You can. Pile the patties, cheese, and fixings into a bowl or use large lettuce leaves as wraps. The sauce is sturdy enough to act as a dressing either way.
Is the sauce really like the Big Mac sauce?
It’s as close as you can get while keeping everything keto and made from common pantry ingredients. The combination of mayo, pickle relish, and a little vinegar hits the same creamy, tangy, slightly sweet notes.
Keto Big Mac Smash Burger Recipe
Ingredients
Method
- In a small bowl, whisk the mayonnaise, sugar-free ketchup, mustard, pickle relish, white vinegar, paprika, onion powder, and garlic powder until smooth. Season with a pinch of salt to taste and set aside.
- Heat a large cast-iron skillet over high heat until smoking. Divide the ground beef into 4 equal portions and roll into balls. Place 2 balls in the skillet, smash each flat with a sturdy spatula and a piece of parchment, and season with the salt and pepper. Cook 2 minutes without moving, then flip, top each with a slice of cheese, and cook 1 minute more. Transfer to a plate and repeat with the remaining 2 balls.
- Spread the sauce on both halves of the keto buns. On each bottom bun, layer lettuce, 4 pickle slices, and 1 tablespoon diced onion. Stack two patties on top and close with the top bun. Serve immediately.
Notes
