Chocolate whoopie pies with marshmallow chocolate filling

These bite size whoopie pies are my third whoopie pie experiment, and the first one that's actually worked yay!

They are about the same size as macarons, so I guess you could think of them as a kind of cakey macaron.

I made these using a brand new whoopie pie tin (who knew you could get these in Australia?)  - thanks to my shopping professional mum, who can find just about anything if asked. I swear one day I'll ask her to find me some sand from the moon landing and I'll get it for my next birthday.

The relevant things about this tin are a) very flat depressions for the whoopie pies, b) it's very heavy and thick so it distributes heat well and cooks the pies through without burning them; and c) it's nonstick.

I made a chocolate mud cake mixture and filled the whoopie tin holes with a teaspoon.

They looked like tiny pikelets. I was worried that they would rise too much and come right out of their holes and spread across the tin, but they were fine.

I gave them ten minutes in the very bottom of an oven heated to 160C.
This is where I really appreciated the quality of the cake pan- because it was so thick and heavy, it distributed the heat really well so that the little whoopie pies didn't burn even though they were so thin.
Also, the nonstick coating of the pan was top class. Some don't really work that well but this one released the pies with only the smallest encouragement from a spatula.

I put the whoopie pies on a rack to cool and started the filling.

This was possibly the weirdest (but one of the nicest) cake fillings I have ever made. It was like nothing I've ever made before, perhaps because I've never experimented with marshmallow.

Chocolate Marshmallow Filling
(from Claire Ptak's The Whoopie Pie Book)

Ingredients
100g dark chocolate
3 egg whites
150g caster sugar
2 tbsp golden syrup
pinch salt

First you need to melt the chocolate over simmering water, in the top of a double boiler saucepan, or you can build yourself a rickety saucepan plus bowl combo like I've done here (above).

Put the chocolate aside to cool a little. Then put all the other ingredients in another bowl and place this bowl on top of the saucepan of simmering water. Whisk the mixture until it's well combined.

At this point the recipe calls for you to beat it by hand for 10-12 minutes. All I can say is that I tried beating for about 3 minutes and my arm nearly dropped off. So I did the sensible thing, and switched to an electric beater.
I didn't know if this would affect it badly so I tried to do it as 'slowly' as you can do with electric - putting it on the lowest setting, only using one beater instead of two, and turning the beater off every 20 seconds to stir manually for 10 seconds. This worked fine.
The mixture slowly becomes very foamy and hot.

Take it off the heat and turn the beater to high speed, whipping up a storm. The mixture will (bizarrely) go much lighter in colour, from a mid brown to nearly white, and will get thicker and thicker - keep beating until it's almost too firm to beat.

Then, very gently, fold in the melted chocolate with a wooden spoon or spatula. This pic shows the chocolate being folded in super gently.

First time I made this, I had a disaster at this point (which I didn't photograph) - I stupidly assumed I could just beat the chocolate in, using the electric beater, just as I had been beating the mixture to its very firm and pale state. But when I tried, the mixture quickly lost all its firmness and turned into a sloppy mess.

The penny dropped when I saw what I had done - it's basically a cooked meringue mixture, with egg whites being responsible for the consistency. When you add other, heavy ingredients to meringue (like melted chocolate) you have to be careful to fold them in really gently because if you beat them in, you will beat all the air out of the egg whites and the mixture will sink. That's what I did with this mixture. I tried to save it by beating up a couple more egg whites to stiff peak and folding them in to firm the mixture, but it was useless - I had to throw it away and start again.

After the chocolate was DELICATELY folded in to the marshmallow mixture, I loaded it into a piping bag and piped a generous dollop onto half of the whoopie pies, then sandwiching them together.

You could just spoon it out but on balance it seemed easier and less messy to pipe it.

To finish them I melted down a small amount of milk chocolate and dolloped it on top, and stuck crystallised violets to it. I love the violet colour with the dark brown of the cake. You could use any type of decoration though.

A quick note, I also had trouble melting the milk chocolate smoothly - probably because I wasn't using couverture, just using a good quality eating chocolate. Well, actually it was a pretty basic quality eating chocolate. It melted patchily and lumpily, and you know what? I just thought 'What the hell,' and used it anyway, and hoped that the crystallised violets would cover up the lumps - which they did.

Key lessons from my chocolate whoopie pie experience:

1. A really solid thick cake pan is a good cake pan.
2. What did people do before nonstick surfaces?
3. Marshmallow filling is awesome and relatively easy to make, and I want to use it more.
4. Don't beat heavy ingredients into egg whites at stiff peak and expect them to like it.