This is very similar to a buttermilk pie I make. Just substitute buttermilk for the regular milk. Also to those having problems with collapsing custards, you may need a better pan. If you can find any of the old Anchor Hocking Fire King baking dishes, they are the best. I collect them. Whenever I see one at a second hand shop I buy it. The heat distribution in them is far superior to metal pans and the newer ceramic or glass pans.
FYI to the diabetics out there (I am one) you can use splenda to substitute for the sugar and calorie countdown milk (it's sugar free) to substutue for the whole milk. It doesn't taste as great as the unaltered recipe, but when you need a large amount of comfort food on a bad day, it will suffice.