For the Filling: Combine the goat cheese and cream in a medium bowl. Using an electric mixer, whip together the cheese and the cream. Season with salt and pepper. Set aside.
For the Herb Oil: Combine the herbs in a food processor and pulse to chop the herbs. With the machine running add the oil, salt, and pepper. Transfer to a small bowl, cover with plastic wrap and set aside.
To serve: Using a serrated knife, cut the tomatoes. Top each tomato with a spoonful of the goat cheese mixture. Place a few tomatoes on a serving plate, drizzle with herb oil, and sprinkle with walnuts. Serve.
Recipe courtesy of Giada De Laurentiis