4 tablespoons olive oil, divided
3 pounds spinach, stemmed and washed
1 pound mixed wild mushrooms
1 cup chicken stock
2 1/2 to 3 pound breast of veal
1 pound veal, coarsely ground
½ Italian sausage, chopped
1 large garlic clove, minced
1 large shallot, minced
1 tablespoon thyme leaves, chopped
2 teaspoons rosemary, chopped
1/4 cup Italian parsley, chopped
Place 2 tablespoons of olive oil in a large sauté pan and brown lightly over medium-high heat. Add the spinach and cook until all its liquid evaporates. Season with salt and pepper. Drain in a strainer and squeeze dry. Chop finely and chill.
Cut large mushrooms into bite-sized pieces. Leave smaller ones whole.
Heat a large sauté pan over medium heat. Add the remaining 2 tablespoons of olive oil. Add the mushrooms. Sauté for a few minutes, until their liquid is exuded. Season lightly with salt and pepper. Add the chicken stock and cover. Braise the mushrooms over low heat for 30 minutes. Uncover and continue to cook until all of the stock has been absorbed, 5 to 10 minutes. Cool the mushrooms before using.
Pound the veal to even thickness, resulting in a large rectangle. Mix together the ground veal, Italian sausage, spinach, mushrooms, garlic, shallot and herbs. Season the stuffing well with 2 teaspoons of salt and some black pepper.
Preheat the oven to 475°. Place the stuffing on the veal leaving a 1-inch border. Gently and tightly roll the veal, securing it with toothpicks or kitchen twine; it's fine if some of the stuffing spills out while the meat is roasting. Season the breast well with salt and pepper and place it in a large roasting pan. Roast in the preheated oven for 20 minutes.
Add 1/2 cup of water to the pan. Reduce the heat to 325° and roast for 1 1/2 to 2 hours longer, until a meat thermometer registers 130°. Let the breast rest covered with foil for 15 to 20 minutes so that the juices have a chance to settle. Remove the breast to a serving plate and drizzle the pan juices over the top. Slice and serve.