In a frying pan preheat olive oil, add thinly sliced onions to the pan and cook on medium heat. Add the chicken broth and bring to a simmer until the onions have started to caramelized and all the juice has been absorbed (this will take about 10-15 minutes). Place the onions to the side. Follow the same steps for the grape tomatoes except you'll want to sweat these out and place them over high heat.
Slice grilled hot Italian sausages in 1/4 inch pieces, chopped sweet bell peppers, and tear the basil.
Begin arranging the flatbreads by smearing 2 tablespoons of Boursin Light Garlic & Herb cheese then sprinkle 1 tablespoon mozzarella and parmesan (each). Place the sliced Italian sausage, peppers, caramelized onions, and grape tomatoes equally amongst the 4 flatbreads. Then sprinkle each flatbread with torn basil; followed by 1 tablespoon each of mozzarella and parmesan cheese.
Place on grill for 5-7 minutes with lid on for 5-7 minutes or until cheese is melted and flatbread is crisp not burnt.
*If your onions begin to burn during the caramelizing process lower the heat and add more broth.