Mix the flour and butter until it is a smooth paste. In a saucepan heat the milk and dissolve the sugar.
Add the vanilla bean and bring to a boil. Add the flour and butter mixture to the boiling milk. With a wire whisk, beat vigorously to ensure there are no lumps. Simmer for several minutes until the mix thickens. Remove from the heat, discard the vanilla bean and cool for 10 minutes in an ice bath.
While the mix is cooling, take 6 3-ounce ramekins or soufflé dishes. Coat with butter and sprinkle with a pinch of sugar. In another mixing bowl quickly beat the egg yolks and vanilla extract and combine with the milk mixture.
Separately beat the egg whites, sugar, and cream of tartar until the egg whites form medium stiff peaks. Fold the egg whites into the soufflé base and pour into the prepared baking dishes and smooth off the tops.
Preheat the Airfryer to 330 F. Place 2 or 3 soufflé dishes into the cooking basket and cook each batch for 12-15 minutes. Serve with powdered sugar on top of the soufflé and with chocolate sauce on the side.