In a large saute pan over high heat, add the oil and when hot, add the onions and saute for 5 to 6 minutes. Add the red chile flakes and garlic and saute for 1 minute longer. Season the chicken with the salt and pepper and add the chicken and cook for 4 to 5 minutes. Add in the mushrooms, zucchini, and canned tomatoes. Add the chicken stock and bring to a simmer. Allow to cook for 5 minutes, and then add the spinach and cream. Cook until heated through and just starting to thicken, about 4 minutes. Finish with the vodka, combine, and turn off the heat. Add the pasta to the pan, combine gently, place on a serving platter or in individual serving bowls, and garnish with the Parmesan and diced tomatoes.