In a large non-stick pan, heat the olive oil over medium heat. Add the mushrooms, cook slowly, stirring often, until deep brown (about 20 minutes). Remove from heat.
Spread a thin layer of marinara pizza sauce over the par-baked flatbread and top with shredded BelGioioso “Secret” Pizza Blend cheese. Evenly distribute the mushrooms, onions and Kalamata Olives over the top of the flatbread and bake for 5-7 remaining minutes, until cheese is melted and crust is golden.
Remove from oven and top with balls of BelGioioso Burrata and fresh basil. Slice flatbread into serving sizes and serve immediately.