Set an oven rack in the lower third of the oven and preheat to 400 degrees F. Brush six 6-ounce ramekins with softened butter, then coat with granulated sugar. Refrigerate until ready to use.
Put the chocolate and butter in a large heatproof bowl. Fill a saucepan with about an inch of water and bring to a low simmer; set the bowl over--but not touching--the water. Heat, stirring occasionally, until the mixture is melted and smooth. Remove from the heat and stir in the vanilla. Set aside.
Combine the egg yolks and 2 tablespoons warm water in the bowl of a stand mixer (or in a large bowl using a hand mixer) and beat until frothy. Gradually add 2 tablespoons of the granulated sugar and continue beating until very thick ribbons form, about 5 minutes. Very lightly fold the yolk mixture into the chocolate mixture.
Put the egg whites in a clean bowl of a standing mixer (or in a large bowl using a hand mixer) and add the cream of tartar. Beat on medium speed until frothy; increase the speed to high and gradually add the remaining 1/2 cup granulated sugar. Beat until the whites hold a stiff but not dry peak, about 3 minutes.
Working quickly, fold about a third of the egg white mixture into the chocolate mixture to lighten; then fold in the remaining whites until blended. Gently spoon the souffle mixture into the prepared ramekins and place on a baking sheet. Lightly smooth the tops of the souffles.
Immediately bake until the souffles rise about 1 1/2 inches from the ramekins, about 18 minutes. In the meantime, make the Triple Raspberry Sauce.
Remove the souffles from the oven, pour some of the sauce over the center of each, dust with confectioners' sugar and serve immediately.
Triple Raspberry Sauce:
In a small saucepan, add the raspberries, sorbet, raspberry jam and lemon zest and set over medium heat. Stir, breaking up the raspberries while it comes to a simmer, then cook until the foam subsides and the mixture becomes thick and syrupy, about 7 minutes. Remove from the heat and swirl in the butter.