Preheat oven to 325?F.
In a large bowl, combine egg, egg yolk, heavy cream and milk and whisk well to combine. Add all remaining ingredients except butter and mix well.
Grease a 7 by 11- or 8 by 12-inch casserole with the butter. Pour custard ingredients into prepared casserole and bake uncovered for 45 minutes, or until custard is set and golden brown on the top.
Yield:†6 to 8 servings