Preheat oven to 425 degrees Fahrenheit.
Bring milk just to a boil. In a steel bowl, whisk egg yolks with sugar for about two minutes. Whisk in flour, strain milk and add to egg yolk mixture, whisking constantly until mixture is smooth.
Transfer mixture to a saucepan and cook over medium heat while constantly whisking. Continue until it will coat the back of a spoon and softens slightly, about 2 to 3 minutes.
Remove pan from heat and strain pastry cream through a fine mesh strainer to remove any lumps. Allow cream to cool slightly until lukewarm.
Whisk passion fruit puree and orange zest into pastry cream.
In a KitchenAid, whisk egg whites while gradually adding granulated sugar, until whites make stiff peaks.
Fold 1/4 of meringue into pastry cream. Gently fold in remaining meringue.
Spoon soufflé mixture into buttered and sugared ramekins, run thumb around the edge of the ramekin to ensure soufflé rises evenly.
Bake in a Bain Marie in the oven for 12 to 15 minutes and golden brown on top.
Carefully remove soufflés from oven, place individually on plate and dust with icing sugar. Serve with chocolate sauce.
In a small heavy pot, bring cream just to a boil. Remove from heat.
Place chocolate pieces in a stainless steel bowl.
Pour heavy cream over chocolate, whisking until smooth.
Refrigerate until ready to use.
Place over a double boiler or Bain Marie and stir occasionally until warm.
If too thick, add a little milk or cream to sauce.