Spray counter lightly with non-stick cooking spray. Combine rolls together and roll into a 15-inch circle. Place in a sprayed 14-inch pizza pan. Turn up edge and pinch to form a rim. Cover with sprayed plastic wrap and let rise while preparing toppings.
In a large skillet, cook onions in olive oil over medium heat 4 to 6 minutes or until soft. Reduce heat to low. Sprinkle thyme over onions and add potatoes. Cover and cook 8 to 10 minutes or until potatoes are tender. Remove from heat and season with salt & pepper.
Remove wrap from dough and poke several times with a fork to prevent bubbles from forming. Pre-bake crust at 350°F 10-15 minutes. Remove from oven and sprinkle with 1/2 of the Swiss cheese. Top with potato mixture. Return to oven and bake 10-15 minutes. Remove from oven and top with corned beef, remaining Swiss cheese and Parmesan cheese. Bake an additional 5-10 minutes or until cheese is melted.