Place oven rack in the very top position of the oven and place pizza stone on it. Heat oven to 550°F.
If refrigerated, set pizza dough on the counter for at least half an hour.
Add the sliced mushrooms to a nonstick skillet over medium high heat. Sauté for 5-10 minutes, until mushrooms have released their moisture and pan is dry. Remove from pan.
Add the bacon pieces and allow to render fat and start to become crisp. Remove bacon from pan and leave fat.
Add 1 tablespoon of butter to pan and allow to melt. Add the leeks and season lightly with salt and pepper (remember the bacon is salty, so you don't need much). Sauté for several minutes, until starting to soften. Add the mushrooms back to the pan and continue to cook with the leeks, until starting to turn golden. Add the bacon and the garlic to the pan and cook until fragrant, 30 seconds to one minute. Taste mixture and season with more salt and pepper if needed. Remove from heat.
Spread cornmeal on to pizza peel. Use your hands to work the pizza dough ball into a disc, when it gets to be 6-8 inches across, place on the pizza peel and continue to spread into a 12 inch disc. If the dough starts to spring back and gets to difficult to work with, let it sit for 10-15 minutes and it should relax. When pizza dough has been shaped into a 12 inch flat disc, give the pizza peel a shake to make sure the dough is not sticking to it.
Use a pastry brush to brush one tablespoon of olive oil all over the crust. Spread the half of shredded cheese all over the dough, leaving about an inch of space all around the outside edge of the crust. Cover with the bacon leek and mushroom mixture. Sprinkle with the rest of the cheese.
Give the pizza peel another shake to make sure the dough is not sticking in any places.
Now comes the tricky part! Transferring the pizza from the peel to the hot pizza stone. This is why you want to make sure your dough isn't sticking to the peel. Open the oven and pull the rack out about halfway so that you have easier access to the hot stone. Quickly, carefully and deliberately, shake the pizza from the peel onto the hot stone, then close the oven. It helps to have two people involved, and for the second person to have a spatula or other heat proof utensil to help guide the pizza onto the stone it needed.
Cook for 8-10 minutes, until crust is golden and cheese is bubbly. Carefully transfer pizza back to pizza peel to remove from oven (again, the second person standing nearby with a spatula is helpful for this).
Allow to sit for a few minutes before slicing and serving.