Heat the olive oil in a large skillet or sauté pan over medium high heat. Cook the pancetta until it is crisp and brown, 2 minutes. Scoop the cooked pancetta out of the pan onto paper towels to drain. Set aside.
In the same pan the pancetta was cooked, sauté the onion, garlic and red pepper flakes until the garlic is golden brown, 1-2 minutes. Add the mushrooms and continue to cook over medium high heat until the mushrooms have browned and the onions are tender 4-6 minutes. Add the clams and wine and stir well. Simmer over medium high heat and remove the clams as they open. Discard any clams that have not opened after 4 minutes.
Stir in the clam juice, tomato sauce, cream, salt and pepper. Bring the sauce to a boil then reduce the heat to medium and simmer to a sauce consistency, 10-12 minutes.
Meanwhile, cook the pasta according to the directions on the package. Drain and return to the empty pot. Pour on the sauce, clams and crisp pancetta. Toss together over low heat until the pasta and sauce are well combined, 1-2 minutes. Stir in the chopped parsley and serve.