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

Directions

1. Preheat oven to 450 degrees.
2. In a large Ziploc bag combine the balsamic vinegar, 2 tbsp olive oil, salt, and pepper. Add the portobello mushroom caps. Zip the bag completely and then shake the bag to coat the mushrooms. Arrange the mushrooms on a baking sheet gill side up. Roast the mushrooms for 12 minutes or until tender and cooked through. While the mushrooms are roasting prepare the caramelized onion topping.
3. Heat a large skillet over medium-high heat with the remaining 2 tbsp of olive oil. Add the sliced red onions, garlic, tomato paste, salt, and pepper. Cook the onions, stirring frequently for about 8 minutes, or until nice and brown. While the onions are caramelizing prepare the ricotta cheese topping for the mushrooms.
4. In a bowl, combine the ricotta cheese and pesto well. Once the mushrooms are done roasting for 12 minutes remove them from the oven and divide the ricotta mixture evenly among the 4 mushroom caps onto the gill side. Return to the oven for about another minute just to heat the cheese.
5. Add the chicken stock and chopped olives to the onions. Turn the heat to high and continue to cook until the stock has reduced almost completely.
6. Arrange one cheese topped mushroom on the bottom of each split roll. Top the cheese with some of the caramelized onions. Top that with two slices of prosciutto and some arugula. Place the top of the roll on, roll up your sleeves, brace yourself with elbows on the table, lean over your plate, and enjoy!