Bete Noir -- no dairy I'd like to try this bete noir recipe, but it's for Passover.  I'd like to make it parve (dairy free).  I'm thinking about substituting butter with margarine (which seems pretty straightforward), and for the ganoche, whipping cream with almond milk (which feels iffier).

Any immediate thoughts on a better approach, or advice for using the almond milk, in particular?? 

UPDATE:  I took the good advice to serve something else, and wait to do this recipe justice.  I was ready -- even found some coconut milk with guar right in it, marketed as a cream substitute, but chickened out.  Made it with whipping cream this week, and it was worth it-- though the ganache is just a thin layer on top of the cake, and I suspect the coconut w/ guar would have worked just fine.
The key to a smooth ganache is fat - add too much water and you will end up with a “grainy” product. There are even recipes that use butter instead of cream (full or partial substitution), and while that’s probably a heart attack on a spoon, the texture is excellent. Almond milk is at least as “watery” as regular cows milk, so yes, that’s a questionable substitute without further changes.

You can benefit from the recent vegan trend and either use full-fat coconut milk (if the flavor is to your liking) or buy a vegan cream substitute, just check what your local store has available. If you want to use almond milk, consider adding a butter substitute (solid vegetable fat?). 

Margarine instead of butter in the crust won’t be an issue, alternatively, you may want to check vegetable shortening. We may have a few Q/As on that substitution on the site. And don’t forget to get dairy-free chocolate.