How to Make It
Preheat the oven to 350°. Butter six 1/2-cup ramekins and set them in a large roasting pan.
Melt the butter in a medium saucepan. Whisk in the flour and cook over moderate heat until lightly golden, 1 to 2 minutes. Gradually whisk in the milk and simmer over low heat, whisking constantly, until the white sauce is thick and has lost its floury taste, about 4 minutes. Stir in the goat cheese, Parmesan, parsley and chives and season generously with salt and pepper. Transfer the sauce to a large bowl and let cool slightly. Whisk in the egg yolks.
In another bowl, beat the egg whites at medium speed until firm peaks form. Stir one-fourth of the egg whites into the white sauce to lighten it, then fold in the remaining whites until no streaks remain. Pour the soufflé mixture into the ramekins, filling them almost to the top. Pour enough boiling water into the roasting pan to reach halfway up the sides of the ramekins. Bake for about 35 minutes, or until golden and firm. Remove the soufflés from the roasting pan using tongs and let cool.
Increase the oven temperature to 425°. Run a thin sharp knife around the rims of the ramekins and invert the soufflés into a 9-by-13-inch glass baking dish. Spoon the heavy cream over the soufflés and bake in the upper third of the oven for about 15 minutes, or until they are nicely puffed and golden on top. Remove from the oven and let stand for 10 minutes.
Using a spatula, carefully transfer the soufflés to plates. In a large bowl, toss the watercress and tomatoes with the warm cream, season with salt and pepper and serve alongside the soufflés.