Balsamic Strawberry Butter Cake

This may be the girliest cake I've made. It's so PINK. My Mum is in town at the moment and we've been planning to celebrate her birthday before she heads back to KL. I'd been struggling to come up with a good idea for her birthday cake, until a recent trip to the Hunter Valley with my favourite ladies where Lisa pointed out the most gorgeous caramelised balsamic vinegar. I immediately knew what I wanted to do; a fluffy vanilla cake layered with Strawberry & Balsamic Vinegar Icing, topped with heart-shaped macarons filled with the same icing.

I love the combination of balsamic vinegar and fresh strawberries. I've previously made balsamic toffee strawberries and was completely enamoured with the flavours. Strawberries are crazy cheap in Australia at the moment, and super sweet and ripe too, which means that there's not much that you need to do to it. All I did was puree the fruit up and mix it into my regular butter icing (like the one I used for the mint chocolate chip cake) along with that amazing caramelised balsamic vinegar. The icing is ridiculously good. It's packed full of strawberry goodness, and has a gorgeous depth of flavour and a bit of tang from the balsamic. It helped that I had that beautiful sweet and thick balsamic vinegar which seemed perfect to use in desserts, but you could use any balsamic you can get and adjust the amount you add to the icing until it tastes just right.

For the cake I decided to try this wonderful looking Fluffy Vanilla Cake from Sweetapolita. I'd had my eye on that recipe ever since she posted it on her lovely blog, and it seemed like the perfect choice to go with this icing. I was having a complete mess of a day in the kitchen, I somehow managed to forget to add the sugar to the cake batter the first time around, and ended up wasting half a dozen eggs (*weeps*) and having to start over. This is why you need to read recipes carefully!! Anyway, second time around I remembered the sugar, and the cakes turned out delicious and golden but not quite as gorgeously light and fluffy looking as the ones on the original recipe. I think I may not have measured the flour quite right so it was a little bit more moist and dense than I wanted, but it still tasted great. Because there's so much detail, great tips and beautiful pictures on the original post, I'm not going to bother copying the recipe on this post and will just point you in the direction of Sweetapolita (if only because you should check out all her amazing cakes even if you're not making this recipe).

I couldn't resist piping some of my heart-shaped macarons to decorate the top of the cake. I remembered how much everyone loved the turquoise coloured macarons on the top of my triple-triple chocolate cake, so this time I decided to embrace the pinkness of the strawberry balsamic icing and made these super hot pink heart macarons. It's so bright and cute, perfect for a girly birthday cake. If anyone is curious about how exactly I pipe the heart shapes, I promised Linda that I would make a quick video the next time I made them, it's kinda dodgy but if anyone really wants to have a look, let me know in the comments and I'll try to upload it, see the end of the post.

I've been having a weird problem with my macarons recently. The last few batches just didn't turn out right, even though it seemed like I was doing the same things I always did. The shells were extra bumpy and taking forever to bake, plus they kept sinking in the middle so they were crunchy and hollow. I was starting to freak out a little. But I did some macaron troubleshooting on the internet and figured out I might have been overmixing my eggwhites, and huzzah! Macarons were back to normal. Relief. And these macarons were so good with the balsamic strawberry buttercream. The strawberry flavour just sang. It really did! I'd be quite happy to whip up this icing to go with so many desserts, it was great with a plain vanilla cake and with plain macarons but I can also imagine it would be great with a chocolate cake, a sponge or a nice cupcake. The icing is the hero.

Balsamic Strawberry Butter Cake with Macarons
(Makes one 20cm cake, cake recipe from Sweetapolita)
For the cake:
Follow instructions to make fluffy vanilla cake here

For the macarons:
100g aged egg whites (you can use fresh eggs too, just make sure they are room temperature. I always use fresh these days, and zap it in the microwave on defrost for 10 seconds)
110g almond meal, at room temperature and well sifted
200g icing sugar
50g caster sugar
Pink powdered food colouring
Optional: 1 tsp powdered egg whites (available from The Essential Ingredient), helps to stabilise egg whites but is not necessary

For the Balsamic Strawberry Icing:
150g (a little over half a punnet) ripe strawberries, hulled
280g (2.5 sticks) unsalted butter
500g icing sugar (about 4 cups), sifted
Approx. 2 tbsp balsamic vinegar, adjust to taste (I used a fantastic caramelised balsamic - a sweeter, thicker balsamic is preferable but any balsamic will do, just adjust to taste)

Prepare the cake using the instructions at the link above. You will end up with two 20cm cake layers. Make sure they are completely cool before icing.

Prepare the macarons; Line two baking sheets with baking paper. Place icing sugar in food processor and pulse for a minute to remove any lumps. Stir in almond meal and pulse for about 30 seconds to combine. Place in a large mixing bowl and set aside. Using an electric mixer, beat egg whites and egg white powder in a medium mixing bowl until the egg white powder dissolves and it reaches soft peaks. With the mixer on high speed, gradually add sugar (and then add food colouring) and beat until it reaches stiff peaks.

Add meringue and to your dry mixture and mix, quickly at first to break down the bubbles in the egg white (you really want to beat all the large bubbles out of the mixture, be rough!), then mix carefully as the dry mixture becomes incorporated and it starts to become shiny again. Take care not to overmix, the mixture should flow like lava and a streak of mixture spread over the surface of the rest of the mixture should disappear after about 30 seconds. Place in a piping bag and pipe rounds of about 3.5cm diameter on baking sheets. Alternatively you can pipe heart shapes using a 1cm piping tip and piping fat 'V' shapes. Tap baking sheets carefully and firmly on the benchtop a couple times to remove any large bubbles.

Leave to dry for about half an hour to an hour, so that when you press the surface of one gently it does not break. This will help prevent any cracking and help the feet to form on the macs. Preheat your oven to 140-150°C (285-300°F), depending on your oven. Place on top of an overturned roasting tray or another baking sheet if your sheets are not professional grade, for better heat distribution. Bake for 15-20 minutes, depending on the size of your shells. Carefully test if the base of the shell is ready by gently lifting one and if it's still soft and sticking to the baking paper, then it needs to bake for a few minutes longer. Remove from the oven and cool on the tray for a few minutes, then gently remove from the sheet and place on a wire rack to cool completely.

Prepare the icing; remove the butter from the fridge 30 mins before starting. Puree strawberries in a food processor or blender (if unavailable you can chop it up and try to mash it through a sieve). Place butter in a large mixing bowl and beat until smooth, fluffy and pale. While beating on medium, gradually add sifted icing sugar and then add the strawberry puree and balsamic vinegar (to taste) and beat on high until smooth and fluffy. You may need to add more puree or more icing sugar to get the right texture, you want it to be spreadable but not runny.

Sandwich macarons together with the icing and place macarons in the fridge while you ice the cake. Spread icing over the top of the one cake layer, about 1/4-1/3 of the remaining icing. Place the second cake layer on top and crumb coat the cake by covering the entire cake with a thin layer of icing. Use the remaining icing to cover the cake with icing. Smooth with an offset spatula (it helps to run the spatula under hot water often before smoothing over icing). Decorate top of cake with macarons. Chill in the fridge for about 30-60 mins before serving.

Edit: Okay here's the link to the crappy video since a couple of people asked :) Sorry it's at a crappy angle, I don't have a tripod so I just kinda balanced my camera on a baking tray. It's not the best example of how I pipe the hearts but you get the general idea, I just pipe a fat 'V' shape. I used the tip of my finger dipped in a bit of hot water to smooth the peaks after I piped them. And umm I only realised I hadn't stuck my baking sheets down to the tray after I started piping, oops. Here's the link.