Penne in Vodka Sauce

From Rachel Ray's recipe

Ingredients:
1 tablespoon extra-virgin olive oil
1 tablespoon butter
2 cloves garlic, minced
1/2 red onion, chopped fine
1 cup vodka
1 cup chicken stock
1 can crushed tomatoes (32 ounces; I used a combination of fresh and can tomatoes
Salt and pepper to taste
16 ounces penne pasta
1/2 cup heavy cream; I used half and half
5-10 basil leaves

In a large pan, swirl the olive oil and add butter, garlic, and onion. Saute onions for 3 to 5 minutes, don't brown. Add vodka to the pan, 3 turns around the pan in a steady stream. Cook till the vodka reduces by half, this will take 2 or 3 minutes. Add chicken/ vegetable stock, and the tomatoes. Bring sauce to a bubble and reduce heat to simmer. Season with salt and pepper. When the oil starts to glisten on the tomatoes, stir in the cream and remove from heat. Cut up half the basil leaves and stir into the sauce.

In the meantime, cook the penne pasta in boiling water al dente. Drain pasta. Toss hot pasta with sauce and remainder chopped basil leaves.