Preheat the oven to 450. In a pan toast the sesame seeds and crushed white peppercorns. Set aside.
Heat a pizza stone for 15 minutes in the oven.
Coat the bottom of a pan with olive oil and bring to medium high heat. Add the sliced onions, fennel and garlic. Saute until caramelized.
Shape the dough to form a large circle, about 12 inches in diameter. Brush olive oil on it.
When the pizza stone is ready, sprinkle the corn meal on the top. Stretch the dough to form that circle and place on top of the stone with the brushed olive oil side down. Brush top lightly with olive oil. Arrange the onions, fennel, scallions, mushrooms and garlic. Sprinkle the toasted sesame and peppercorns on top. Layer the all the cheeses ending with the shredded mozzarella. Lastly sprinkle the salt flakes and your selected spice(s).
Bake for 20-25 minutes until golden brown. Add fresh herbs just before serving. Good luck trying to have some leftovers for breakfast.