Butter an 9 x 13-inch shallow baking dish with the 2 tsp. softened butter. In a large skillet, melt 1 Tbs. of the butter. Add half the bread cubes and sauté on medium to medium-high heat until the corners are barely golden, about 2 minutes. Dump the cubes into the baking dish. Repeat with the remaining 1 Tbs. butter and the rest of the bread.
Pour the milk and cream into a medium saucepan. Stir in the sugar, salt, cinnamon, nutmeg, and vanilla bean, if using. Heat over medium high, stirring once or twice until the sugar dissolves and the milk is hot. Remove from the heat. If using vanilla extract, stir it in now. If using a vanilla bean, cover the sauce pan and let steep for 10 minutes.
In a large mixing bowl, whisk together the eggs and yolks. Slowly pour about 1/2 cup of the hot milk mixture into the eggs, whisking constantly. Gradually whisk in another 1/2 cup, and then the remaining more quickly. With a rubber spatula scrape any vanilla seeds from the saucepan into the custard.
Pour the custard over the bread, pushing down the cubes to moisten them all. Lay plastic wrap directly on the pudding and let sit, pressing on the plastic frequently to submerge the top layer, until the bread is thoroughly soaked, 30 to 35 minutes. While the bread soaks, adjust an oven rack to the center position. Set a roasting pan, large enough to comfortably hold the pudding, on the rack. Pour in hot water to come one-quarter of the way up the sides. Heat the oven to 350°F.
Remove the plastic wrap from the pudding. To make the topping, sprinkle on the raisins and press them partly into the pudding. In a small bowl, mix the sugar with the cinnamon and nutmeg and sprinkle this evenly over the top. Dot the pudding with 1 Tbs. butter.
Set the pudding in the roasting pan; if the hot water doesn't come halfway up the sides, add more until it does. Bake until a wooden skewer inserted in the center comes out clean, 40 to 45 minutes. Remove from the water bath. Serve warm.