Why did my pizza toppings slide off while baking?

I made a New York-style pizza using recipes from the Elements of Pizza book by Ken Forkish, and some of the cheese and pepperoni slid off in the oven while baking. This was my first time using these recipes and a baking steel.

I believe I followed the recipes pretty faithfully, measured everything by weight, etc. The steel preheated in my home oven at 500°F for about 45 minutes to an hour as the manufacturer recommended.

The book says to cook the pizza for nine to ten minutes. About five minutes in, I could hear something sizzling. When I peeked into the oven I could see the dough had puffed up, and some of the pepperoni and cheese appeared to have flowed over the edges in a couple places and was burning up on the steel.

My pizza went in the oven looking like this:

It came out looking like this:

Why did this happen and how can I avoid it?

Edit: added photos of second attempt with a smaller overflow.

Top edge where overflow occurred:

Close-up of top edge:

• I don't bother to edit in this case because temperature is not that important here. But: please don't write just “degrees” when you mean Fahrenheit. Write °F or simply F or literally Fahrenheit, and if temperature is important to the question please consider also showing the Celsius translation. Jul 26, 2022 at 16:05
• Is your baking surface level? Perhaps as the cheese becomes a "liquid" it spills over the "container", just as glass full of ice tilted at an angle might melt and spill over Jul 27, 2022 at 19:01

It likely comes down to how you've formed the crust. The "normal" method involves pushing the gas out of the middle of the crust, ideally shifting it to the outer edge. So the middle of the crust ends up fairly thin and dense, and the outer edge has more remaining bubbles. If you pull out the crust more gently, and don't squeeze the gas out, then it'll rise like a loaf of bread rather than like a pizza.

The other possibility is that the crust somehow sealed to your baking surface around the edges, and vapor puffed it up and away from the baking surface in the middle. That would be indicated by the underside of the crust having a dark rim and a very pale middle. I've never seen this happen, and I'm not sure it actually could, but I thought I'd mention it for completeness.

• If you want to be a bit lazier and not manually work the air to the edge, you can dock the dough. Tapping the tines of a fork, the blunter the better, into the dough with good coverage will eliminate the majority of the bubbles that are going to cause serious rise. You of course do not dock the edge of the crust. Jul 26, 2022 at 16:10
• Yep, good point. I don’t think the advantage of dining is necessarily laziness — seems like more work than just shoving on the crust — but it can give you a thick, airy crust which doesn’t go crazy on you. Jul 26, 2022 at 18:24
• I re-read the section where Forkish instructs "leaving about a 1/2 inch (12.7mm) of the outer rim un-deflated", and I think I pushed it too far. I added photos of a second attempt where I tried to leave that intact but still screwed up one part. You can see a kind of "high-cheese mark" around the top of the second crust, except on the edge at the top of the photo which is clean and under-baked. Peeking during the second one, I think what I originally thought was the dough puffing up was actually all of the cheese puffing up. Jul 26, 2022 at 19:00
• FWIW, it definitely wasn’t the cheese puffing up. Cheese doesn’t do that. (Well, except American cheese but that’s a different situation.) It’s pretty easy to leave the rim intact as long as you’re not using a rolling pin. If you’re f flattening the crust enough and still seeing puffing in the middle, docking is perhaps the way to go. Though I’d happily eat either of those pizzas. Jul 26, 2022 at 19:52
• Just to add to this: the purpose of docking is not to poke holes in the dough that go all the way through. Rather, docking compresses and "cements" together the docked spots. During baking, if there are any air bubbles in the middle, when they expand, they can only grow as large as the area between 2 docked spots. This prevents the bubbles from being able to grow large enough to force toppings away and poof up. Oct 22, 2022 at 17:13

I think it's probably bubbles, as mentioned in other answers. Since you have a relatively thin crust you can try docking your dough. Docking means pressing dots into the dough so that small bubbles form instead of large ones (like crackers that have a pattern of dots). They make special tools to do this quickly but you can also do it with a fork, just remember that the goal is to press the dough together to break up bubbles, not actually go all the way through.

I see two possibilities, the first is that the toppings slid off when you slid the pie off the peel, the other is that the pizza puffed up when baking and the toppings slid off then.

If the pizza base sticks to the peel the tendency is to tip it up and try and shove it off, which can send your toppings flying. The trick is to use plenty of semolina or coarse corn meal between the base and the peel so it slides off. Keep the pizza flat while you do this, with enough semolina you'll find the pizza comes off the peel with just a bit of forward push.

It's also possible that the base was thicker in the middle than the sides, and it puffed up when it was in the oven and your toppings slid off. To remedy this make a lip at the edge of the crust, so the edge is just a bit thicker than the rest, that way when the crust expands the edge rises more and forms a barrier. A slightly raised edge will also help keep your toppings from coming off when you slide it off the peel. Also make sure that the middle of the pizza base isn't thicker than the rest.

Additionally, here are some useful tips:

1. Pepperoni sometimes curls before cooking, when topping the pizza put the edge of the curls downward so there's more contact to keep it in place
2. Press the pepperoni into the pizza a little bit

It's a great looking pizza despite the topping sliding, a couple of tweaks and you're home free.

• What makes you think the OP is having issues with the crust sticking to the peel? Jul 26, 2022 at 9:50
• Because that happened to me when I first started making pizzas @Sneftel , it wasn't coming off the peel cleanly so I had to use force and toppings slid off.
– GdD
Jul 26, 2022 at 10:40
• Sure, me too, but the OP didn’t mention anything about that. It sounds like the pizza went in fine, and then when they checked later it had gone wrong during cooking. Jul 26, 2022 at 11:45
• The crust didn't stick to the peel going in the oven; I was a bit surprised it in went smoothly. @GdD point taken about the lip, I could've done that better. Jul 26, 2022 at 12:20
• My approach to answers is to make it applicable to others who may have had the same issue. In this case the pizza may have gone in fine - although that wasn't apparent in the question - but for others it could be the cause.
– GdD
Jul 26, 2022 at 12:24

It doesn't look like dough/crust bubbles to me, because those usually don't deflate without obvious signs. Cheese usually falls off of crust bubbles.

The pepperonis aren't the only thing that moved; the cheese also spread. It looks to me like the cheese just carried the pepperonis with it.