Sunday, 21 July 2013

The Wedding Cake Saga - Part 4 - Icing

Because I was determined that I wasn't going to be covering this cake in fondant, I knew I would have to make massive quantities of Swiss meringue buttercream (SMB from now on) to finish the cakes. SMB is a lot less sweet than American style buttercream. It's made by pasteurising egg whites and sugar over boiling water (not as scary as it sounds), then whipping them up to firm peaks and then gradually whipping in chunks of butter. It has the texture and consistency of a firm whipped cream. It's easy to spread onto cakes (and scrape off any mistakes!!) and is a pleasure to work with as long as you don't get any crumbs in it (being almost pure white, these are very noticeable, especially on dark cakes!).

whipping, whipping, whipping...

I'd only ever made small (well, 'normal') quantities of SMB before. I calculated roughly that I would need 12 egg whites, and being that a general rule of thumb is 50g of sugar per egg white, that I needed 600g of sugar. Because I had no use for the yolks, I decided to freeze them, I hear they freeze rather well, and I had heard of an ingenious tip of freezing them in individual ice cube trays so they are already portioned out. One egg yolk fit perfectly in each cube. To use them after freezing you defrost them in the fridge, give them a bit of a stir and use them as you normally would, but for more information I'm sure you'll find what you're looking for in a quick google search.

for some reason this was oddly satisfying!

I was worried once I'd made the SMB that it wouldn't be enough, I had to crumb coat and ice three large cakes. The amount I had made didn't look like that much in the bowl (despite the fact that I had to whip it in two parts because it was giving my kitchenaid great stress, see above photo!) and I thought about making more, but we were running out of eggs (me having used 34 for the icing and cakes combined) so I thought I'd see how it went. I needn't have worried. I ended up with quite a bit left over. I wouldn't make less than this next time, simply because I liked the 'wiggle room' and security of having such a large quantity at hand, knowing I wasn't going to run out towards the end. You can easily scale this recipe down for a normal cake, using 50g of sugar per egg white. A 2-3 egg white mixture will give you plenty for a normal 8-10'' cake, and a 1 egg white mixture is perfect for filling and covering a 6'' sponge.

Swiss Meringue Buttercream
Enough to generously ice a three tiered cake with some leftovers

12 egg whites
600g granulated sugar
a pinch of salt
approx. 750g of butter (I used a combination of butter and Trex - a vegetable shortening - this gave me a much brighter white than I would have gotten with just butter while still keeping a good taste, and made the buttercream more stable)

1. Mix your egg whites, sugar and salt in a metal bowl.
2. Place the bowl over a pan of barely simmering water, making sure that the bottom of the bowl isn't touching the water directly.
3. Cook the mixture over the gentle heat slowly, stirring constantly until when you rub a bit of the mixture between your two fingers you can't feel the sugar grains. What you're doing here is dissolving the sugar in the egg whites, but at the same time pasteurising the whites so they're safe to use. Make sure the heat isn't too high and that you keep on stirring the mixture slowly, otherwise you'll end up with scrambled egg whites!
4. As soon as all the sugar has dissolved, remove the bowl from the heat, tip mixture into a clean bowl and whisk with an electric or stand mixer until cool (as I made such a large amount it would have taken ages for the mixture to cool, so I stopped when firm peaks were achieved) at this stage the mixture will have fluffed up a lot and look like meringue mixture does before it's cooled, you should also be able to turn the bowl upside down without any mixture falling out like you can with real meringue mixture! It was at this point that I had to separate my mixture into two batches because my mixer was struggling.
5. Gradually add chunks of butter/shortening while the mixture is beating. The egg white mixture will change consistency pretty quickly. It will go softer, and maybe even 'soupy' (luckily this didn't happen to me this time but it has happened before! If this happens put your butter/shortening and your egg white mixture into the fridge for about 15 minutes, as the icing has got too warm. Cold ingredients will help it firm up much more quickly) but persevere and keep adding butter/shortening until you get something that holds its shape very well on the beaters of your mixer. At this stage you can also add any flavourings and or colours (gel or paste food colourings will give the most vibrant results if using). If you're using them, I recommend that they be clear 'extracts' and not highly coloured (if not using additional colours), as this will ruin your perfect buttercream, unless you're going for a coloured look, of course.

Actually icing all the tiers was both a great pain and great fun. First came the crumb coat, to seal in any stray crumbs ready for the next and final layer of buttercream. The crumb coat is really just a scrape of SMB, so this was pretty easy. I didn't have to worry about catching crumbs - this was the point. After all the cakes were 'dirty iced' it seemed like the cake was starting to come together as a whole, and look slightly more professional that just another home made sponge. After I finished the crumb coats I had to give the cakes a bit of time to set up in the fridge as they never would have set at room temperature (even though, mercifully, the temperature has been a few degrees cooler than yesterday, I don't think neither the cakes, nor I would have withstood 28/29 degrees again!) which was a bit of a problem as the cakes were quite big (and especially quite tall). After several minutes and moving of lots of shelves I cleared a space big enough for the baking tray I had put the cakes on.

After the cakes had chilled I had to ice them properly. I was so nervous about getting crumbs in the final coat all the cakes have a layer of buttercream about half an inch thick. Nothing wrong with that, though. I'd rather them be like that and be crumb free than have specks of cake flecked through the icing that I couldn't do anything about (especially on the chocolate tier - that was the hardest and the most nerve wracking!) I found that the easiest pattern to do on the sides of the cakes was to drag the spatula very gently around the cake while spinning it on the lazy susan, so your spatula stays in the same place and you spin the cake with your other hand. Be sure to press very lightly, you only want to make a slight impression in the icing, too far and you'll pick up loads of crumbs and your hard work will be ruined. The horizontal pattern also made it really easy to go back and cover up any mistakes, stray crumbs were covered with just another swipe of buttercream. I was really pleased with how the tiers turned out, actually, I think the pattern looks a lot trickier than it was.

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