1 tablespoon olive oil
1 cup loosely packed fresh flat-leaf parsley leaves, coarsely chopped
2 whole boneless chicken breasts, skin on, split
Salt and freshly ground pepper
1 small onion, chopped
10 white mushrooms, trimmed and cut into 1/4-inch pieces
1 cup of white wine
2 tablespoons balsamic vinegar
2 tablespoons butter
4 handfuls ( 8 to 10 ounces) fresh baby or flat leaf spinach, stems cut

1- Heat oven to 400 degrees.
Heat olive oil in a large skillet over medium heat.
Press a scant tablespoon parsley onto skin side of each breast
Season both sides with salt and pepper.
Place breasts, skin-side down, in skillet;
cook until golden, about 8 minutes per side.

Remove chicken from skillet:
transfer to a roasting pan.
transfer pan to oven until chicken cooks through.
15 to 20 minutes.

Meanwhile, return skillet to stove.
add onion; cook, stirring until just golden, about 2 minutes.
Add mushrooms: cook until soft, about 5 minutes.
Add wine: scrape skillet's bottom to released cooked-on juices.
Cook until wine ia almost evaporated, about 5 minutes.
Add vinegar: cook 1 minute more.
Stir in remaining parsley;
Season with salt and pepper.
Remove from heat; stir in butter.

4- Remove chicken from oven
Place spinach on plates.
Slice each breast into sixths; arrange over spinach.
Spoon mushroom mixture over chicken, drizzling juices over
spinach, and serve.