The soufflé, meaning “to puff up,” is a delicate French cake made simply of combining egg yolks with beaten egg whites and just a few of other ingredients. The combination of custard and egg whites causes the pastry to puff up when baked, hence the name.
Preheat the oven to 350 degrees F.
Butter the inside of 6 ramikins and use the 1/4 cup of sugar to coat the inside of each, making sure to cover all the interior surfaces. Set aside the prepared soufflé dishes.
In a medium saucepan over low-medium heat, bring 1 cup of milk just to steaming. In a separate large bowl, stir together 1/3 cup granulated sugar, egg yolks, 1/3 cup flour, and the remaining 1/3 cup milk until it forms a smooth batter.
Slowly whisk 1/3 of the hot milk into the batter, making sure to combine the ingredients until they are completely smooth. Add the tempered batter back into the hot milk in the pan and bring the mixture to a simmer, stirring constantly. Stir and cook the mixture until it has thickened, for about 1 minute. Stir the butter into the mixture and allow it to cool at room temperature for 10 minutes. Stir in the vanilla extract.
In the bowl of an electric mixer fitted with a whisk attachment, whisk the egg whites on medium high speed until they become just foamy, and then add the remaining 2 tablespoons sugar. Continue whisking the egg whites on high speed until they hold stiff glossy peaks and can hold when turned upside down on the whisk.
Gently fold 1/3 of the egg whites into the vanilla batter mixture, then carefully fold in the remaining whipped egg whites. Be careful not to overmix, a few streaks are better than deflated egg whties.
Spoon the soufflé mixture into the prepared dishes and bake for 25 to 30 minutes or until the soufflé has risen with a crusty exterior. Serve the soufflé with a dusting powdered sugar.