Long ago I made a Gateau Mocha (a flourless cake) with chocolate buttercream frosting and served a wine to compliment the blackberry and raspberry garnish that was with the cake. My thinking at the time was that if I went to emphasize the chocolate, it would emphasize the heaviness and be a bit too much ... whereas if I went for the berries, it would emphasize that part of the dish. So even though you are serving beer, in part emphasizing any fruit garnish (with your beer selection) might lighten such a heavy dessert.
Before I get to the beer recommendation ...
As far as a garnish? ... big juicy raspberries, blackberries? ... fresh currants? ... strawberries? ... maybe even candied cherries such as used on a Black Forest Torte?
Either way, I think whether matching a not-too-sweet cake (verses a really sweet one) ... or a berry garnish ... it is more similar than it might seem.
The cake can stand a bit of sweetness (if it was a sweet cake you would not serve a sweeter wine or beer with it) ... and the berries need the sweetness to level out the acidity.
SO ... for beer ... I think it could be helpful to look at how a wine would match up and why, first ...
For matching wine to the berry garnish as I did (yes, by way of this explanation, this will apply to your chocolate cake ... read on) ... one would want a slightly sweeter wine - not a really dry one as a dry one emphasizes the acid component of the berries too much (as does tannin) ... but also a wine not so sweet that it overwhelms the subtle flavor and sweetness of the berries themselves. As you don’t want a particularly tannic wine, it means that reds are generally out ... you also would not want the overbearing tannin with the heavy chocolate either ... you want to “lighten” the chocolate.
So, as tannic wine is out ... I would say that this means that a very hoppy beer is out.
With that Gateau I made, I went with an Asti (Tosti Asti Spumante actually ... ok, yeah, hey it was the 1980’s.) which worked well both with the berries and with the chocolate. Sweet but not too sweet even tho it was a muscat grape.
The Asti was lowish in alcohol (again the heaviness thing) ... moderately sweet, fruit/berry aromas, not tannic, and very *sparkly* ... a good thing with such a heavy cake (this was why I did not go with something like a sauterne which was a runner-up in my choice).
One problem with the heavier stouts or porters etc is that the effervescence might not be quite vibrant enough to stand up to the heavy cake too.
So ... an effervescent beer ... fruit/berry notes ... some sweetness but not too much ... not high gravity ... little hoppyness ...... I’m going to say a witbier.
and for me ... there would be no question about the first beer I’d reach for ..... Hoegaarden!! ...
effervescent, citrus and a bit of spice, not too heavy or sweet, clean finish ... refreshing verses the heavy chocolate cake.
Great flavors verses the chocolate ... and one to contrast and lighten as well.
(yes I know, a lot to wade through for a beer recommendation ... they don't call me "Jacob the Brief" for nothing)
