Ultimate Smash Burger
with Caramelised Onions

There are burgers, and then there's the Smash Burger. Popularised by diner culture and perfected in backyard kitchens across America, the smash burger's genius lies in technique: a ball of loose-packed beef slammed hard against a screaming-hot cast iron skillet creates maximum surface contact, developing a deeply caramelised, lacy, crunchy crust that no regular burger can replicate. Add two layers of American cheese, slow-cooked jammy onions, and our secret smoky mayo, and you have the most satisfying burger you will ever eat.

What You'll Need

• 500g 80/20 ground beef (chuck), loosely packed
• 4 brioche buns, split and butter-toasted
• 8 slices American cheese (Kraft singles or similar)
• 2 large yellow onions, thinly sliced
• 2 tbsp neutral oil (vegetable or sunflower) for cooking
• 1 tsp Maldon sea salt, plus more for seasoning
• 1 tsp freshly cracked black pepper
• 4 tbsp smoky burger sauce (see tip below)
• 1 head iceberg lettuce, shredded
• 2 large ripe tomatoes, sliced
• 8 bread-and-butter pickles

How to Make It

1. 1

   Caramelise the Onions

   Heat 1 tbsp oil in a wide heavy-bottomed pan over medium-low heat. Add the sliced onions with a pinch of salt and cook slowly for 35–40 minutes, stirring occasionally, until deeply golden, jammy, and sweet. Don't rush this — low and slow is the key. Set aside. This can be done up to 3 days ahead and refrigerated.

   
2. 2

   Prepare the Beef Balls

   Divide the ground beef into 8 loose balls of approximately 60g each — don't overwork the meat. The looser the pack, the lacier the crust. Season generously with salt and pepper just before cooking. Keep refrigerated until the moment they go in the pan.

3. 3

   Get the Pan Screaming Hot

   Place a cast-iron skillet over the highest heat possible for at least 4–5 minutes. It should be almost smoking. Add 1 tsp neutral oil and let it shimmer. You need maximum heat to achieve the Maillard reaction — the deep, crusty caramelisation that defines a smash burger. Do NOT use a non-stick pan.

   
4. 4

   Smash & Sear

   Working in batches of 2, place a beef ball in the skillet and immediately press it down firmly and firmly with a heavy flat spatula (or burger press) for 10 full seconds. You want it to spread to about 12cm across. Season the top with salt and pepper. Cook for 90 seconds, until the edges turn grey and the underside is deeply browned and crusty. Flip once.

5. 5

   Cheese and Stack

   Immediately after flipping, lay a slice of American cheese on each patty. Cook for 30 more seconds. For a double cheeseburger (highly recommended), stack two patties. The cheese should be fully melted and beginning to ooze over the edges. This is the moment. Transfer to a plate.

   
6. 6

   Build the Burger

   Generously spread smoky burger sauce on both cut sides of the toasted brioche bun. Bottom bun: sauce, shredded lettuce, tomato, pickles. Stack the double patty. Top with a heaped spoonful of warm caramelised onions. Crown with the top bun. Press gently and serve immediately with fries and more sauce on the side.

Nutrition Facts

Per serving (1 double burger). Values are approximate.

Nutrient	Amount	% Daily Value
Calories	—	760 kcal
Protein	—	48g
Total Fat	—	42g
Saturated Fat	—	18g
Carbohydrates	—	38g
Sugars	—	12g
Fibre	—	3g
Sodium	—	980mg