I used to turn the same ingredients into a tart, but it was such a hit the one time I substituted pizza dough for pastry that I’ve been making it this way ever since. This always gets polished off at parties with a lot of praise. I prepare the flatbread at home, then cook it on site.

Steps

1. In a large skillet, fry the bacon over medium heat until just cooked, but not crispy. Remove the bacon from the pan and set it aside to cool. When cool, cut the cooked bacon into small squares.
2. If you have a nice layer of bacon fat in the pan, say a quarter to half an inch, toss in the onions. Otherwise, add enough olive oil to the pan to make up the difference. Cook the onions, with a big pinch of salt and a healthy grind of black pepper, over medium-low heat for 30 to 40 minutes, stirring occasionally. You want them to be golden brown, soft, and sweet. Once they are cooked, turn off the heat.
3. Preheat the oven to 400 degrees.
4. On a lightly floured surface, roll out the prepared dough into a large rectangle, about a half-inch thick. Transfer the dough to a lightly oiled baking sheet (or a floured pizza peel if you are going to cook the flatbread on a pizza stone) and stretch the dough as much as you can, without tearing it, into the largest rectangle you can.
5. Spread the cooked onions over the dough, leaving a half-inch margin around the edges. Sprinkle the grated mozzarella over the onions. Crumble the goat cheese in your hands and sprinkle it over the mozzarella. Top with the bacon and sprinkle on the red pepper flakes.
6. Cook for 10 to 15 minutes, until the crust is golden brown and cooked through and the cheeses have melted.
7. Remove from the oven and let cool for at least 5 minutes, allowing the cheese to set. Cut into squares and serve.