If using pizza dough, roll it out onto a baking sheet lined with parchment paper to create a flatbread shape. If using store-bought flatbread, simply place it on the baking sheet.
Brush the surface of the flatbread or dough with olive oil, ensuring an even layer.
Arrange the tomato slices evenly over the flatbread, leaving some space between each piece for even cooking.
Scatter the mozzarella pieces over the tomatoes.
Season the flatbread with salt, pepper, and red pepper flakes if desired.
Bake in the preheated oven for 12-15 minutes, or until the cheese is bubbly and slightly golden, and the edges of the flatbread are crispy.
Once out of the oven, let it cool for a minute. Drizzle balsamic vinegar over the top and scatter fresh basil leaves.