Allow your pizza dough to sit out and come to room temperature.
Preheat oven to 475 degrees. If using a cast iron skillet preheat your cast iron skillet in the oven.
Heat a large skillet over low heat and add the olive oil. Add the onions and cook for 10 minutes.
Sprinkle the sugar over the onions along with a pinch of salt. Allow them to cook on low until caramelized, stirring often.
Add the pears, wine, and balsamic vinegar and stir to combine. Allow the mixture to cook until most of the liquid has evaporated and the pears are tender, but not too soft.
Stretch out your pizza dough to the size of the cast iron skillet. Carefully remove the skillet from the oven and grease it. Lower the crust into the skillet and drizzle it with olive oil.
Top the pizza dough with the onion and pear mixture. Crumble the Boursin cheese over the top. Sprinkle thyme on top.
Bake the pizza for 15 minutes, or until the crust is golden brown and the cheese beginning to melt.