Preheat oven to 350ºF. Lightly butter an 8-inch covered baking dish. Place the oats and 2 tbs. butter in a medium bowl. Pour boiling water over. Let stand 5 minutes. Stir in milk, sugar, cinnamon, salt, and currants or raisins. Spoon mixture into prepared baking dish. Bake, covered, for 30 to 35 minutes, or until bubbling. Serve with extra milk.