This onion and bacon tart (also known as flammekueche or flammkuchen) is said to have been created by Alsatian bread bakers to test the heat of their ovens. At peak temperature, the tart would cook in just one or two minutes, the edges of the thin crust nearly burned by the heat of the flames, hence the name. Tarte flambee is traditionally topped with fromage blanc but this version uses goat cheese thinned with some heavy cream. You can also easily modify this dish based on what you have available: ricotta, cottage cheese, or even cream cheese. You can make the crust with whole-wheat pizza dough or puff pastry instead, adjusting the baking time and temperature, as needed. Whatever crust or topping you choose, the tart makes for a wonderful appetizer, cut into small pieces.
Set a rack in the lowest position of the oven and preheat to its highest temperature (at least 450 degrees F).
Place the bacon in a large, heavy-bottomed skillet or Dutch oven; cook over medium-high heat, stirring occasionally, until the fat is rendered, but the bacon is not yet totally crisp, 5 to 7 minutes. Add the onions and stir well to coat evenly in the bacon fat. Cook, stirring occasionally, until all of the bacon is nearly crisp and the onions are almost caramelized, about 7 minutes. Remove from the heat and let cool in the skillet.
Meanwhile, place the dough on a lightly floured work surface and roll out into a long, thin oval. If the dough keeps shrinking back, let it relax a bit before trying again. Transfer the dough to a large floured baking sheet.
Whisk the goat cheese in a medium bowl until smooth (if necessary, microwave for about 20 seconds to melt it a bit). Add the cream and whisk until combined. Spread evenly over the dough, leaving a 1/4-inch border all around.
Top the cheese with the bacon and onions, drizzling on any bacon fat from the skillet. Season generously with pepper and a bit of sea salt.
Bake until the edges of the crust are golden and crisp (they may bubble up a bit--that's okay), 10 to 12 minutes.
Remove from the oven and let cool for at least 5 minutes before cutting and serving. Serve hot, at room temperature, or even cold.