chicken potpie casserole

This might be the first dinner I make at our new place. And it looks very easy, especially if I buy the chopped onion, carrot, and celery mix from Trader Joe's.

Ingredients:
2 tablespoons extra-virgin olive oil, plus more for brushing
1 small onion, finely chopped
2 stalks celery, halved lengthwise and cut into 1/4-inch pieces
1 large carrot, peeled, quartered lengthwise and cut into 1/4-inch pieces
Salt and pepper
One 8-ounce container sliced mushrooms
2 tablespoons flour
3/4 cup heavy cream
1 store-bought rotisserie chicken, meat torn into 1/2-inch pieces (about 4 cups)
2 tablespoons finely chopped flat-leaf parsley, plus more for sprinkling
1/2 cup grated parmesan cheese, plus 2 tablespoons for sprinkling
Six to eight 1/2-inch-thick slices Italian bread

Directions:
1. Arrange a rack in the lower third of the oven and preheat to 400°.

2. In a large skillet, heat 2 tablespoons olive oil over medium heat. Add the onion, celery, carrots, 1/2 teaspoon salt and 1/4 teaspoon pepper and cook until crisp-tender, about 5 minutes. Increase the heat to medium-high. Add the mushrooms and cook until tender, about 6 minutes. Sprinkle the flour on top; stir for 1 minute. Stir in the cream and simmer, stirring occasionally, until slightly thickened, about 3 minutes. Stir in the chicken, parsley and parmesan; season with salt and pepper.

3. Transfer the chicken mixture to an 8-inch-by-10-inch baking dish. Trim the bread slices to fit on top of the chicken mixture in an even layer. Brush with olive oil and sprinkle parsley and the remaining parmesan on top. Bake until crispy, about 15 minutes.

(from Every Day with Rachel Ray December 2009)