2 C cold milk
1/3 C sugar
3 Tbsp cornstarch
1/4 tsp salt
1/2 tsp vanilla
1 Tbsp butter

Mix together sugar, cornstarch, and salt in a small saucepan. Wisk in cold milk until completely dissolved. Warm over medium heat, stirring often, until it becomes thick enough to coat the back of a spoon. Do not allow to boil. Take off heat and incorporate vanilla and butter. Pour into individual dishes and cool for at least two hours.