How to Make It
Preheat the oven to 350°. Butter an 8-by-4-inch inch loaf pan. Sprinkle the raisins on the bottom. In a bowl, combine 1/4 cup of the sugar, the cinnamon and nutmeg. Whisk in the egg, cream and vanilla. Add the bread. Let stand for 5 minutes, stirring occasionally, until the liquid is absorbed.
Spoon the bread into the prepared loaf pan and smooth the top. Bake for 25 minutes, or until golden and set. Let cool slightly, then turn the bread pudding out onto a cutting board and coarsely chop it.
Butter a 3-cup ramekin or soufflé dish and sprinkle it with sugar, tapping out any excess. In a clean bowl, using an electric mixer, beat the egg whites with the cream of tartar until frothy. Increase the speed to high and beat until soft peaks form. Gradually add the remaining 1/4 cup of sugar and beat until stiff and glossy. Put half of the bread pudding in a medium bowl. Fold in one-fourth of the beaten egg whites until just combined. Spoon the mixture into the ramekin. Add the remaining bread pudding to the bowl and fold in the remaining egg whites. Spoon the mixture into the ramekin, mounding it about 1-inch above the rim. Bake the soufflé for 25 minutes, or until golden and puffed.
In a small saucepan, bring the cream to a boil. Whisk in the dissolved cornstarch and cook until slightly thickened, about 1 minute. Off the heat, add the sugar and bourbon. Return to the heat and simmer over moderately low heat for 1 minute.
As soon as the soufflé is done, poke a hole in the center and pour in half of the bourbon sauce. Serve the soufflé at once, passing the extra sauce on the side.