Congrats on the certification! That pie looks delicious, especially coming out of that oven!
Frankie G - Here is an overview of leoparding, but by no means the end of the conversation:
Leoparding is achieved with higher hydration, combined with long fermentation and the right cook temp. If you have a larger oven, you can actually control the size of the blisters by having the pie father away from the direct flames. This also correlates with temperature.
For example, a 62% hydration dough that has gone through 24 hours of room temp fermentation, will easily leopard at the right temperature. That same pie, cooked at a lower temperature, will show signs of leoparding, but not pronounced spots.
Another example: a 60% dough fermented with commercial yeast for 8 hours will not show leoparding easily at any temp. It will lean toward the description given above for VPN standards.
The below pics show a short (4 hour) and a long (24 hour) ferment, with 61% and 64% hydration respectively.