Combine all ingredients in bowl of a large mixer. Mix with a dough hook for 5 to 7 minutes, scraping the bowl occasionally, until dough forms a sticky ball on the end of the hook. Transfer dough to a greased bowl and cover with plastic wrap. Let rise in a warm place until doubled, approximately 1 hour. Punch down and divide into 6 equal pieces. Place 1 piece of dough on a floured board and coat with flour. With a floured rolling pin, roll out dough into a rough rectangle, approximately 10 inches to 12 inches across and 1/8-inch thick using plenty of flour on both sides of dough at all times. Repeat with remaining dough. Place on parchment-lined cookie sheets. Cover and refrigerate while you prepare the topping. Dough can be prepared 1 day in advance, wrapped and refrigerated, until ready to roll.
For the topping: In large bowl whisk together first 8 ingredients.
Preheat oven to 500 degrees F. and place racks close to bottom of oven. Spread 1/2 cup topping on each piece of rolled dough. Sprinkle with onions and then bacon. Bake until brown and crisp, approximately 10 minutes, rotating sheets midway through to brown evenly. Repeat with remaining dough and topping. Cut into squares and serve immediately.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.
Recipe courtesy of Raymond Ost, Sandrines, Boston, MA