Add the remaining 3 tablespoons of olive oil
to the saucepan
and heat until just shimmering. Add the beef, veal and pork and cook over moderately high heat until just barely pink, about 5 minutes. Return the vegetable mixture to the saucepan
. Add the garlic and cook over high heat until fragrant, about 1 minute. Add the wine and cook, stirring occasionally, until almost evaporated, about 8 minutes. Stir in the tomatoes and their juices, the chicken stock, thyme and bay leaf
. Season with a generous pinch of salt and pepper and bring to a boil over high heat. Cover partially and cook over moderately low heat for 1 hour. Discard the bay leaf
. Stir in the heavy cream and cook the sauce just until heated through.