Adjust oven rack to lower-middle position and heat oven to 450 degrees.
Spread each pita with 3 tablespoons fig jam. Top each with generous 3 ounces cheese and sprinkle with 2 tablespoons nuts. Place on a large baking sheet and bake until cheese melts and crust is golden brown and crisp, about 10 minutes.
Remove pizzas from the oven, topping each with optional prosciutto; let stand a few minutes for prosciutto to warm. Serve, cutting each pizza into 8 triangles if being served as an appetizer.
Recipe by Three Many Cooks at https://threemanycooks.com/recipes/nibbles-and-apps/fig-brie-and-walnut-pizza/