1/4 cup (1/2 stick) butter
Heat oil in heavy large skillet over medium-high heat. Season chicken with salt and pepper. Add to skillet and sauté until just cooked through, about 3 minutes per side. Cool slightly. Thinly slice chicken crosswise and set aside.
Melt butter in same skillet over medium-low heat. Add leeks and garlic and sauté until leeks are very tender, about 10 minutes. Stir in tomatoes, vermouth and chicken. Cook until mixture is just heated through, about 2 minutes. Season generously with salt and pepper. Combine chicken mixture, linguine and 1/2 cup Parmesan in large bowl; toss well. Sprinkle with basil if desired. Serve, passing remaining Parmesan.