When mixing the custard : Keeping all ingredients at room temperature will keep the melted butter from solidifying in the custard when cold milk hits it.
The pie baked in my oven on a cookie sheet for the full 60 minutes. I checked at 45 minutes, the custard had puffed up on the sides of the pie, but not in the center. I continued baking until the center of the custard was puffed up as well. Then I removed the pie from the oven.