Step 1Heat the oven to 325 degrees. Grease the bottom and sides of a 13x9-inch glass baking dish with butter.
Step 2Cut the bread into 1-inch cubes and spread them evenly in the pan. Sprinkle with the raisins.
Step 3Mix together the cream, half-and-half, sugar, vanilla, cinnamon, nutmeg, eggs and salt in an electric mixer on low speed until smooth, 2 minutes. Pour over the bread and raisins, pressing down on the bread cubes so the custard covers them.
Step 4Fill the bottom of a large pan with water to come up half an inch on the sides. Place the bread pudding pan inside the larger pan and bake until the pudding is browned on top and a knife inserted near the center comes out clean, 1 hour, 15 minutes. Remove the pudding dish from the larger pan and let it cool 5 minutes. Cut into pieces and serve.