Preheat oven to 375ºF. Brush the ramekins with butter and dust evenly with the extra sugar. Discard excess sugar.
Pour the milk in a saucepan and cook on a low heat. Using the point of a knife, scrape the seeds from the vanilla bean pod into the milk, and bring to the boil.
Beat the sugar and the egg yolks in a bowl until pale yellow, thick and creamy, then add the flour and mix well.
Remove the vanilla bean pod from the hot milk. Add half of the hot milk into the egg yolk mixture and mix well. Return the egg yolk mixture to the saucepan and on a low heat stir continuously and whisk until the cream thickens. When the egg yolk mixture starts boiling remove from the heat and keep stirring. Transfer the yolk mixture to a larger bowl and let it cool slightly.
In a stand mixer or a large bowl, whisk the egg whites until you get soft peaks. Add the sugar and the cream of tartar. Gently fold the meringue into the yolk mixture.
Divide the soufflé mixture evenly into the ramekins you prepared and run your thumb around the inside rims of each ramekin. Bake for 23-25 minutes until golden and puffed.
Remove from the oven and dust the hot soufflés with powdered sugar. Also add your favourite sauce!! Serve immediately. They will usually fall after about 3-5 minutes.