I baked Bernachon Palet d’or gateau as per the recipe and it was lovely and had great flavour. However I would have preferred the texture to be less dense, lighter and less hard when refrigerated. Hence, I was thinking of replacing some of the butter with oil (e.g 150 gms of butter and 50gms of oil). Has anyone tried this?

Any suggestions would be appreciated.

I have not tried this, but if you are looking for a cake that stays soft in the refrigerator, consider the deep chocolate passion (used for baby cakes, German choc cake, ice cream cake and wedding cake).

Rose does offer a bundt cake which is a chocolate butter cake with a little oil subbed for some of the butter, but it is a much smaller proportion of oil than what you are proposing. 

If you do try it, please post back and report your results!

Hi

I am thinking, adding oil will surely make the cake stay softer as oil is unsaturated fat. However, adding oil will not give you a cake which is less dense. Oil will make the batter more runny and runny batters will not have as good an ability to hold air as compared to fluffy and thick batters. Air is what that makes a cake fluffy. Hence, substituting part of a butter will no doubt make your cake tender, but the fluffiness will be adversely affected