How to make the perfect smash burger on your flat top grill, according to a pro chef

Tom's Guide

27-05-2025

It's Get Grillin' Week here at Tom's Guide, and while we're reviewing everything from the best grills to upright smokers, there's a method of grilling that's growing in popularity in 2025. That's flat top grilling, and it's thanks to the rise of brands like Blackstone, and new models such as the Weber Slate.
While it might seem more accessible than grilling methods such as gas and charcoal, flat top grills also require a bit of trial and error. That's why I jumped at the chance to attend a smash burger masterclass with the founder of my favorite takeout joint, Nanny Bill's. Well, that and the promise of free burgers.
Feasting aside, I picked up some incredible tips from founder Darren Simpson on how to recreate my go-to takeout burger from home, or even my yard. Here are three tips to achieving that perfect smash burger on your own griddle.
The most important part in making a smash burger is that initial sear, Simpson told me.
"Getting that contact with the grill to get a good sear is the number one most important thing when cooking a burger," he said. "If you don't get that initial sear, it's hard to get a good crust on your patty, which is what gives it that delicious caramelization."
It took a bit more welly than I'd expected, but using a sturdy burger press I put my patty down on the piping hot griddle and smooshed it with both arms. The sizzling noise was a sign that I was creating that ideal smashed crust.
You want a burger with a flat pressing surface so you can get a perfectly even press on your burger patty. This options has a heat-resistant handle that will allow you to get a good grip burger after burger.
And if you want to do the same on a traditional grill?
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"Smash them onto a super-hot cast iron skillet set over grill grates for four minutes," says Simpson. "That will trigger the Maillard chemical reaction, which gives burgers that deep, savoury crust and umami flavour, all without drying out the meat."
Maybe I'm just impatient, but I tend to flip my burgers a few times throughout cooking to make sure I'm not burning my meat. According to Nanny Bill's, that's a big mistake.
"You want to do about 70% of cooking on the first side of the burger," Simpson told me.
We added some mustard to the top side of our patties before flipping, which creates a glaze and additional caramelization when you flip your patty. According to Simpson, "it elevates the beef to another level."
We let our burgers cook for a few minutes, until the meat on the top side was nearly brown. By this point, the burgers had achieved a deep brown crust and released the perfect amount of fat to toast our buns.
"This next step is quite unique to us," Simpson told me. I'd added some steam to my burger cooking before, but I'd never done it with a bun on top.
First, we stacked our (cheese-topped) patties before adding our freshly-toasted top bun. Then, we use a drizzler bottle full of water and spread a little in a circle around our burger. We then topped it with a lid — "you can use a metal mixing bowl", says Simpson — and let it steam for around 30 seconds.
This heats up the bun and gives it a soft, fluffy finish. It also melts the cheese, combining the two patties before you place them on top of your bottom bun.
Nanny Bill's calls this a "cheese sauna," which is definitely a term I'll be adding to my grilling lexicon.
It's worth noting, you should add your sauce to the bottom of your burger bun before you follow this step, and add any salad (admittedly, my burger was totally vegetable-free) to the base bun before you assemble.
One homemade smash burger later, Nanny Bill's filled me in on some more tricks of the trade to take home for your summer barbecues.
It turns out, a lot of the important steps for creating the ideal smash burger involve prepping the right ingredients, and making sure yout meat is flavorful and well-rested.
So there you have it — all the tips you need to make the perfect smash burger in your own backyard. Just call me Nanny Mill's.