Butter a 1 ½ quart souffle dish with 2 tablespoons of butter.
In a large saucepan, bring the milk to just below a boil. Slowly whisk in the cornmeal and bring to a boil again. Lower the heat to medium and constantly whisk the mixture until it thickens and begins to pull away from the sides of the saucepan, about 6 to 7 minutes. Remove from the heat and transfer to a large mixing bowl. Let it cool off for 10 minutes.
Whisk in the 3 tablespoons butter, salt, and sugar. Beat in the egg yolks until well blended.
In a clean large mixing bowl, beat the egg whites and cream of tartar to soft glossy mounds. Stir in one-third of the beaten egg whites into the cornmeal mixture to lighten. Gently fold in the remaining egg whites and slowly pour the mixture into the souffle dish.
Bake for 30 minutes or until puffed and golden brown, Cool 10 minutes before serving.