Place the active dry yeast and sugar in a bowl of an electric mixer (or a large bowl) and give it a little stir to mix. Add warm water, stir well, and let it bloom for about 5 minutes.
Start the mixer or "stir" setting and add flour, salt, and olive oil. Mix the dough, still on stir, setting just until combined.
Lightly flour the work surface and take the dough out of the bowl and onto the work surface. The dough will still be slightly tacky. Sprinkle a little bit more flour over the top and knead the dough with your hand just a few times.
Rub some olive oil all over the inside of the bowl and place the dough into it. Cover the bowl with plastic wrap and then a clean kitchen towel. Place the bowl into a warm, dry area and let it rise for an hour.
Note: you can make flatbread dough ahead of time and store it in the refrigerator. Make sure let it rise for an hour first, before refrigerating. See storing instructions in recipe notes.
Caramelized onions and cook bacon:
While the dough is rising, that's a good time to prepare the toppings.
For bacon, cut raw bacon into small pieces. Preheat a large cooking pan over medium heat and add a little bit of olive oil. Cook bacon pieces until completely done. Strain off the fat (save a couple of tablespoons to cook onions) and set bacon bits aside.
Add a couple of tablespoons of bacon grease back into the pan and add sliced onion. Lower the heat to medium-low, season the onions with some salt and sugar, and mix well.
Stir onions every 5-10 minutes as they cook and slowly get golden brown. The total time will take about 45 minutes. Don't try to rush it or raise the heat because the onions will sear instead of caramelizing. Wait for them to naturally caramelize and brown. Once browned, set aside.
Grate the cheese and set it aside.
Prepare the flatbread pizza:
Preheat the oven to 500° and line a large (or two smaller) baking sheet with parchment paper.
Divide the dough in half and roll out each half into thin flatbreads, about 1/4 inch thick.
Place them onto the prepared baking sheet and give it a little space in between.
Prebake the flatbreads for about 7-9 minutes, until the dough is golden.
Take the dough out and divide the grated Gruyere cheese, caramelized onions, and bacon bits among the two flatbreads. Make sure to spread the toppings evenly.
Place it back in the oven until the cheese is melted.
Take the flatbread out, slice, and serve.
Preparing the dough ahead or time: You can prepare the pizza dough and the store it in the refrigerator for a couple of days. It’s important to let it rise first though, so prepare the dough and still give it an hour for the initial rise to activate the yeast. Once the dough is ready, you can divide it into two pieces or store it in one piece. Gently rub the dough with some olive oil and either place it into a bowl and cover it airtight with plastic wrap, or place it into a lightly greased zip-top gallon bag. Either container you use, make sure it is airtight! Stored properly, the dough will stay fresh in the refrigerator for about 2 days.