In a small saucepan, cook the dried mushrooms in the stock at a low, rolling boil until the mushrooms soften and the liquid reduces slightly, 10 to 15 minutes.
Meanwhile, in a large, deep skillet, heat the EVOO over medium-high. Season the chicken with salt and pepper and cook, turning once, until browned on both sides, 6 to 8 minutes. Transfer to a plate.
Add the butter and sliced fresh mushrooms to the skillet and cook until lightly browned, then add the shallots, garlic, thyme and parsley stems and season. Stir in the tomato paste and cook 1 minute more. Add the tomatoes and the marsala and bring to a simmer. Add the porcini mushrooms and reduced stock. Return the chicken to the pan and cook through, 5 to 10 minutes. Garnish with the chopped parsley leaves; serve with the bread.