Combine the egg yolks, milk, vanilla, 3/4 cup of the sugar, cinnamon, and nutmeg and whisk until the sugar dissolves. Place the bread pieces in a large 10-cup rectangular or oval casserole dish. Pour the yolk and milk mixture over the bread and let it sit for about 30 minutes, mashing the bread occasionally with a fork.
Dot the top of the bread and milk mixture with the butter. Place the casserole in a larger baking dish or roasting pan and fill the dish with enough water to come halfway up the sides of the casserole.
Bake for about 1 1/2 hours, or until the pudding sets and a knife inserted into the pudding comes out clean. Remove the pudding from the oven and remove from the water bath.
Beat the egg whites with the remaining 6 tablespoons sugar until they form stiff peaks for a meringue.
Increase the oven temperature to 425ºF.
Spread the meringue evenly over the top of the pudding, going all the way to the edges of the casserole. Return the casserole to the oven. Bake for about 15 minutes, or until the meringue is lightly browned.
Remove from the oven and cool on the counter for about 15 minutes.
Yield: about 10 servings
Melt the butter in a double boiler over simmering water. Add the sugar and whisk to dissolve. Add the bourbon and whisk for 1 minute.
Remove from the heat and drizzle in the egg yolks, whisking constantly.
Return the double boiler to the heat and continue whisking until the sauce is pale and slightly thickened, 3 to 4 minutes.
Spoon the sauce over the pudding and serve immediately.