In a medium bowl, lightly beat eggs. Stir in milk, sugar, vanilla, and salt. Place a 1-quart casserole or six 6-ounce custard cups in a 13x9x2 baking pan on oven rack. Pour custard mixture into casserole or cups. Sprinkle with nutmeg, if desired. Pour boiling water into the pan around casserole or custard cups to a depth of 1 inch. Bake at 325 for 50 to 60 minutes for the 1-quart casserole, 30 to 40 minutes for the custard cups, or until a knife inserted near center comes out clean. Serve warm or chilled. To unmold chilled individual custards, first loosen edges with a spatula or knife, then invert onto serving plate.
Variation: Baked Coffee Custard Prepare as above, adding 4 tsp instant (decaf) coffee crystals dissolved in 1 Tbsp hot water to eggs along with milk, sugar, etc. Omit nutmeg. Serve topped with whipped cream, sprinkled with toasted almonds.