Set the oven rack in the middle position. Preheat the oven to 275F. Prepare a 1 1/2-quart ovenproof glass baking dish by buttering it or coating it with vegetable spray. Cover a 14-inch by 16-inch baking pan with foil, shiny side up. Coat the foil with vegetable spray or use a silicone liner.
Sift together sugar, salt, cinnamon, ginger, and nutmeg in a bowl. Add cornmeal and stir to combine.
Cook 3 cups of the milk in a heavy bottomed saucepan over medium heat,stirring with wooden spoon, just until scalded and bubbles form around the edges. Remove from heat. Add dry ingredients slowly, stirring with a wooden spoon. Place pan over low heat and continue stirring until mixture begins to thicken. Spoon a small amount of hot pudding mixture into egg mixture to temper it. Add egg mixture to pudding in pan and continue stirring until thick. Remove from heat and stir in butter.
Pour pudding into baking dish. Pour remaining cup milk over top,but do not stir in. Bake 2 1/2 to 3 hours, or until pudding has a warm brown crust pulling away from the sides of dish. Pudding will be set but will still wiggle a bit. Place on a rack to cool.
Serve warm with vanilla ice cream and Maple Spiced Nuts. Store pudding covered with plastic wrap and in the refrigerator.