BBC Bitter Chocolate Cake recipe - problems

[ArranBrown]

I'm having trouble with the first in the 'Have Your Cake' recipes:

http://www.bbc.co.uk/...ourcake_recipes.shtml

I used 85% chocolate and got a very greasy mixture which oozed oil while cooking, and then broke when I attempted to split it. My latest attempt is stuck together with the recommended icing. The first time I tried I used 70% chocolate and don't recall having these problems. If I'm going to use 85%, what other adjustments do I need to make to the quantities of other ingredients, or do I just use less chocolate? You'll see the cake is unusual in that it uses mayonnaise in place of eggs and butter. I should add that the result tastes very good, despite its tendency to self-destruct when handled.

I would appreciate some guidance, please.

[Mojo-Jo-Jo]

Most recipes call for 70% chocolate. Maybe you should just stick to that?

[ArranBrown]

As you'll see, the recipe simply said 'good, dark chocolate'; it didn't specify a percentage. I thought 'surely 85 is better than 70' but it would appear not, in this case.