1. Caramelize the onions: In a large skillet, heat the olive oil and butter over medium heat. When the oil is hot, add the sliced onions, tossing to coat. The heat should be high enough to create some color/char on the onions, but not burn them. Cook for 15 minutes, until the onions develop some initial caramelized color. Reduce the heat to medium-low and add the salt, pepper, brown sugar. Deglaze the pan by adding the balsamic vinegar and scraping up any browned bits at the bottom of the pan. Continue to cook on medium-low for 20-25 minutes, stirring occasionally, until the onions are very deeply browned (refer to picture for what they should look like!)
2. Preheat and pan prep: Preheat oven to 450 degrees and place a pizza stone on the bottom rack of the oven while it preheats. If you don’t have a pizza stone you can use a sheet pan. If using pizza dough, sprinkle a little semolina flour or cornmeal on a pizza peel or cutting board so it’ll slide right off onto the pizza stone.
3. Assemble flatbreads: Roll out the pizza dough into two rectangular pieces or skip this step if using premade flatbread. Spread the jam evenly over the dough/flatbread. Layer on: chopped bacon, caramelized onion, gruyere cheese and then crumbled goat cheese. Remove thyme leaves from several sprigs and sprinkle on the flatbread.
4. Bake and garnish: Transfer flatbread to the preheated pizza stone or pan and bake for 10-12 minutes, until the bottom is crispy and cheese is melted. Top with fresh arugula, a drizzle of balsamic glaze and extra virgin olive oil and pinch of flaky sea salt.

Serve immediately to your fancy flatbread friends. Or eat it all yourself, I won’t judge.