Cheese burns before the base cooks

What you're seeing

Four or five minutes in and the top of the pizza is already too far gone — black blistered patches across the cheese, pepperoni with burnt rims, maybe a slick of orange oil where the cheese has split. You lift an edge with the peel and the underside is barely coloured. Turn the grill off next time and you get the opposite pizza: a properly baked base under cheese that is melted, greasy and completely blond. There does not seem to be a setting that gives you both.

The short answer

Your oven's top and bottom are not balanced, and the cheese is losing the race by several minutes. Fix it from the base up: get the slab genuinely hot so the base needs less time, move the pizza further from the grill element, and choose a cheese with enough fat to survive the heat. Adding the cheese partway through the bake is the fallback that always works.

Why it happens

Top and bottom heat arrive by different routes

The base cooks by conduction — direct contact with a slab that has stored energy and dumps it into the dough. The top cooks by radiation from the grill element and the hot oven roof, which travels at the speed of light and does not care how well you preheated anything.

That means the two halves of the pizza are on independent timers, and only one of them is under your control before the bake starts. A steel that has had 60 minutes at maximum delivers enough energy in the first 90 seconds to cut a bake from eight minutes to five, and those three minutes are exactly the ones that were destroying your cheese. A slab that has had twenty minutes leaves the base needing a long bake under an element that will not wait for it. This is the burnt base with raw toppings problem turned upside down, and it has the same root: the balance between the two, not the absolute temperature of either.

Radiant heat falls away fast with distance

Move a pizza from 10 cm below the grill element to 20 cm and the radiant load on the cheese drops sharply — the intensity falls off steeply as the distance grows. Most people bake pizza on the top rack because they read that it browns better, which is true, and then leave the grill running for the full bake, which is not what that advice meant. The top rack plus a full-time grill is a cheese incinerator.

Cheese browns at the surface, and drying decides where

Melted mozzarella browns through the same Maillard chemistry as the crust: milk proteins reacting with lactose, plus a little caramelisation. Like every browning reaction it needs the surface to dry first. As long as a patch of cheese still has moisture and molten fat over it, it stays around 100 °C (212 °F) and colours gently. The moment a patch dries — usually a high point, a thin edge, or a spot that was already low in fat — its temperature runs away and it goes from golden to black in under a minute.

Fat is the buffer. Whole-milk low-moisture mozzarella is required to carry not less than 45% milkfat in its solids; part-skim sits between 30% and 45%, and in practice most of it is at the bottom of that band. That fat melts out and spreads across the surface, keeping it wet and levelling out the hot spots. Less fat means drier cheese, sooner, and scorching that starts before the base has finished — which is why the mozzarella guide treats whole milk rather than part-skim as the specification for a home oven, not as an indulgence. Fresh mozzarella behaves differently again — it floods rather than burns, which is its own problem.

Shred size matters for the same reason. Finely grated cheese has far more surface per gram and dries almost immediately; 1–2 cm cubes or a coarse shred hold their moisture through the bake and melt into a mat instead of crisping into a lid.

Fix it now

1. Preheat the slab 45–60 minutes at maximum, timed from when the oven reaches temperature. Everything below depends on this.
2. Drop the pizza one rack. Aim for 18–20 cm between the top of the pizza and the grill element for the main part of the bake.
3. Bake with the grill off, finish with it on. Bake until the base is set and coloured, then run the element for the last 60–90 seconds only, standing at the door and watching.
4. Put the cheese on partway through if the base still needs longer. Launch with sauce, bake to about 60% done, scatter the cheese, finish. It needs 2–3 minutes, no more.
5. Switch to whole-milk low-moisture mozzarella, cubed or coarsely shredded, and keep it to 100–120 g on a 30 cm base.
6. Put pepperoni under a little cheese, not on top of it. Exposed thin slices curl and burn several minutes before a covered one does.
7. Tent with foil as a last resort. It works, it stops the burning, and it also stops the browning — use it to rescue tonight's pizza, not as a method.

Prevent it next time

• Build a dough that suits a longer bake. A malted bread flour around 12.7% protein at 60–63% hydration colours and crisps at home-oven temperatures where a soft 00 stays pale, so you are not forced to run the grill to compensate. The bread flour against 00 comparison covers the trade.
• Use a steel rather than a stone. Steel conducts around 18 times faster than cordierite (~45 W/m·K against ~2.5); a baking steel buys back minutes on the base, which is time the cheese never has to endure.
• Learn your oven's balance once. Bake a plain sauced base with no cheese and watch which surface finishes first. That one observation tells you the rack position for every pizza afterwards.
• Keep the cheese off the rim. Cheese pushed to the edge sits closest to the element and has no sauce underneath to keep it cool.
• Weigh the toppings on a New York pepperoni once, then work from the picture in your head. Overloading forces a longer bake, and a longer bake is what burns cheese.
• Set the dough for the oven you own with the New York settings — a 5–7 minute bake at 250–290 °C (480–555 °F) is what those ratios are aimed at.