Ricotta Smothered Mushroom "Burger" with Sweet Onion-Olive Topping, Prosciutto, and Arugula by Pretend Chef

Between a toasted Kaiser roll is a marinated portobello mushroom cap smothered in ricotta cheese with a basil pesto topped with caramelized onions in a tomato paste with kalamata olives, layered with 2 slices of prosciutto, and then a handful of…