Split vanilla bean lengthwise and scrape seeds into small saucepan; add pod and milk and bring to boil. Remove from heat, cover and let steep for 15 minutes. Remove vanilla pod.

Butter 3-cup/750 mL soufflé dish; sprinkle bottom and side with 1 tbsp/15 mL of the sugar.

Beat 2 of the egg yolks with about half of the remaining sugar until light; beat in flour, then gradually whisk in milk mixture. Pour into saucepan and, whisking constantly, bring to boil; boil, stirring, for 30 seconds.Scrape into bowl; let cool.

Beat in remaining yolk. Beat egg whites with cream of tartar until in stiff but not dry peaks; beat in remaining sugar until in stiff glossy peaks. Fold egg white mixture into yolk mixture until no white streaks remain; scrape into prepared dish.

Bake in centre of 375F/190C oven until well-puffed, centre is set and top is golden brown, 25 to 30 minutes.

Chocolate Sauce: Meanwhile, place chocolate in heatproof bowl. Bring cream to boil; pour over chocolate and stir until chocolate is melted. Place bowl over hot (not boiling) water; stir in butter and brandy until butter is melted. Keep warm over hot water until serving; serve on side.

Makes 2 to 3 servings.