Making Lemon Shortbread cookie. Have no vanilla. Any suggestions to a substitute?

I will try the almond. Thanks for coming to the rescue!

I'm with A&M on this one, and think a 1/4 to 1/2 the amount of almond would be lovely with the lemon. I'd also consider doing a second version with lime instead of lemon and coconut instead of vanilla - but I'm crazy like that! Spicesetc has a really nice coconut natural flavoring. Alton Brown also has a recipe for homemade coconut extract that is really nice (and could make a great little cook's gift).

I vote for almond too, and a smaller amount of it. A drop of coconut (as long as it's high quality exttact) could also be good.

This is purely a matter of taste preference. You won't "hurt" the recipe by leaving it out and not substituting another extract. I may suggest sticking with one of the citrus extracts if you really want to add this ingredient.

I'd do almond, but half the amount, because it's strong. I think the citrus extracts will take away from the lemon zest flavor, and coconut extract is a heavy flavor. You could also skip the extract and they'll still be great!