Tarte Flambée Végétarienne

1. Preheat oven to 220°C (425°F). If using pizza dough, roll it out very thinly into a rectangle or oval. 2. Heat olive oil in a small skillet over medium heat. Add thinly sliced onions and cook for 5-7 minutes until softened and lightly caramelized. Add sliced mushrooms and cook for another 3-5 minutes until tender and browned. 3. In a small bowl, season crème fraîche with salt and pepper. 4. Spread the seasoned crème fraîche evenly over the flatbread or pizza dough, leaving a small border. 5. Distribute the caramelized onions and mushrooms over the crème fraîche. 6. Bake directly on the oven rack or on a baking sheet for 10-12 minutes, or until the crust is golden and crispy, and the topping is bubbling. 7. Remove from oven, slice, and garnish with fresh chopped chives before serving. Serve immediately.