Ingredients

4 servings

　　1/4 cup balsamic vinegar (eyeball it)

　　4 tablespoons extra-virgin olive oil (EVOO)

　　Salt and freshly ground black pepper

　　4 large portobello mushroom caps

　　1 large red onion, thinly sliced

　　2 large garlic cloves, chopped

　　1 rounded tablespoon tomato paste

　　1 1/2 cups whole-milk ricotta cheese

　　3 tablespoons store-bought pesto sauce

　　1/2 cup chicken stock or broth

　　1/3 cup (a couple of handfuls) pitted kalamata olives, chopped

　　4 crusty kaiser rolls, split in half, toasted or not—it’s up to you

　　8 thin slices prosciutto di Parma (optional)

　　1 small bunch of arugula, washed and trimmed of any thick stems

　　

Step 1

Preheat the oven to 450°F.

　　

Step 2

In a shallow bowl, combine the balsamic vinegar, about 2 tablespoons of the EVOO, salt, and pepper. Add the portobello mushrooms and toss to coat. Arrange the mushrooms on a cookie 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.

　　

Step 3

Heat a medium-size skillet over medium-high heat with the remaining 2 tablespoons of EVOO (twice around the pan). 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.

　　

Step 4

In a bowl, thoroughly combine the ricotta cheese and the pesto. Once the mushrooms have roasted for 12 minutes, remove them from the oven and divide the ricotta mixture evenly among the 4 mushrooms, spreading it onto the gill side of the mushrooms with the back of a spoon. Return to the oven for about a minute, just to heat the cheese.

　　

Step 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.

　　

Step 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 2 slices of prosciutto and some arugula. Finish it off with a roll top. Eat and enjoy!

　　Rachael Ray 365: No Repeats