A yellow face opaline blue cock mated to a blue spangle hen will produce some female yellow face opaline spangles.
There are other ways to go about it but it is important that the opaline comes from the male because it is a sex-linked mutation. The yellow face and the spangle gene can come from either parent. If the opaline comes from both parents you would get YF opaline spangles of both sexes
Your Willow must be split for opaline so if he was mated to a blue spangle hen you should get some yellow face opaline spangles