How to Make It
Heat the oven to 400°. Cut off the top third of the head of garlic and save it for another use. Rub the cut head of garlic with 1 tablespoon of the oil and sprinkle with a pinch each of salt and pepper. Wrap in aluminum foil and roast in the oven until the garlic is soft, about 45 minutes. When cool enough to handle, scoop out the flesh with a small knife.
In a large pot, bring the stock to a boil. Reduce the heat, add the roasted garlic, parsley stems, thyme, bay leaves and peppercorns and simmer until reduced to 2 quarts, about 30 minutes. Strain the stock.
Meanwhile, in a large pot, heat the remaining 2 tablespoons oil over moderately high heat. Add the carrots and cook, stirring occasionally, for 5 minutes. Add the cabbage and cook, stirring, for 5 minutes. Add the spinach, 1/2 teaspoon salt and a pinch of pepper and cook, stirring, until all the vegetables are soft, about 5 minutes. Remove the vegetables.
In the same pot, melt the butter over moderate heat. Add the mushrooms, 1/4 teaspoon salt and a pinch of pepper and cook, stirring, until beginning to brown, about 5 minutes. Add the tomato and basil and cook, stirring, for 1 minute. Add the stock, carrots, cabbage and spinach to the pot.
On a clean work surface, lay out a few of the wonton wrappers and brush lightly with water. Put about 1 1/2 teaspoons of the mascarpone in the center of each wonton, fold into a triangle and seal. Join the two bottom points and seal. Repeat with the remaining wonton wrappers.
In a pot of boiling, salted water, cook the mascarpone cappelletti until just done, about 3 minutes, and drain. Add the cappelletti to the soup and bring just to a simmer. Serve topped with the Parmesan.