Dough undercooked in centre

[omens]

New kitchen. New electric oven goes up to 300°C, which is far higher than my old one that maxed out at 220°C.
I tried Vito Iocapelli’s Neapolitan pizza and it came out beautifully.

I have since tried various New York style pizzas- on a screen but on the rack, on a screen but on steel, and directly on baking steel 6mm). Today’s attempt was Brian Lagerstrom’s takeaway pizza. I made the first pizza with dough and sauce, cooked for 4 mins, added cheese and cooked for another four mins. The second pizza I assembled and cooked altogether for 8 mins. No difference either way. In every case, the cornichione is cooked, the base is cooked, the cheese is cooked, the dough between is undercooked/gelatinous. 

I use type 0 Manitoba flour

Am I running the oven too hot?
Should I cook just the dough and add sauce/cheese later?

[Cheazy E]

I’m not familiar with the recipe, but takeaway implies thicker, “American Style.” You are likely onto the primary issue. I’d try 260-270 degrees Celsius and allow for a longer bake time. The style is thicker and needs extra time at a lower temp.

You may also be using too much sauce, but the style usually calls for a relatively thicker tomato base.

[wotavidone]

Try brushing the stretched skin with olive oil before putting on the wet sauce?

[Yael]

The gummy line can come from many issues, here are the ones I think about:
- too much sauce/toppings/wetness
- stone not hot enough (not enough conduction heat)
- not properly fermented dough (heat doesn't go through the crust)

Recently I had a problem of uncooked dough under the sauce because of these 2 first points combined.