GBBO 2017 Week 1 - Technical - Chocolate Mini Rolls

When I heard what the title of the technical challenge of this week's GBBO was, I wondered "why?" (like what the bakers thought I imagined). Mini rolls, in case you don't know, are basically mini chocolate Swiss rolls filled with cream/buttercream and covered in chocolate. They're a popular addition to children's lunch boxes in the UK and I used to love them when I was little. I don't know if they exist in the USA, but there's probably something similar?

Now I've tried Swiss roll sponges in the past and have had mixed results. This seemed like a perfect opportunity to test out Prue's skills as a recipe writer, and maybe fix my historical issues with this flourless sponge.

Prue used peppermint extract in her buttercream, but my partner hates mint, and as blackberries are in season at the moment, I decided to add these to the filling of my mini rolls, which was simply flavoured with vanilla extract.

I only had a few issues with this bake. The first was that the recipe states to use two 20 x 30cm Swiss roll trays (normal baking trays are fine as long as their sides are at least 1cm tall) - I only own one 20 x 30cm tray, my other is bigger (about 36 x 25cm). This meant that my mini rolls didn't end up very uniform, but as I'm not in the tent, I don't think anyone will mind!

My second issue was just the quantity of buttercream the recipe said to use. I needed to loosen the buttercream (which wasn't suggested in the recipe) with a little milk, and needed to make more than was suggested.

Apart from that though, the sponge was easy to make, inexpensive as it used cocoa rather than melted chocolate, and came out really fluffy and chocolate-y. I was very impressed.

Makes 12 mini-rolls (but they're not that mini! Serve one per person).

Ingredients:

For the mini rolls:

• 60g (2/3 cup) cocoa powder (the best quality you can afford)
• 30g (2 tbsp) melted butter, plus an extra spoonful to grease two trays
• 1 tsp vanilla extract
• 4 tablespoons boiling water
• 6 eggs
• 150g (3/4 cups) caster sugar

For the filling:

• 200g (7/8 cup) softened butter
• 400g (2 cups) icing sugar, sifted
• 1 tsp vanilla extract
• Around 50g (around 3/8 cup) blackberries, washed

To finish:

• 250g (1 & 2/3 cups) milk chocolate
• 250g (1 & 2/3 cups) 70% dark chocolate
• 50g (1/3 cup) white chocolate

Method:

1. Preheat the oven to 180c (160c fan)/ 355f/ gas mark 4. Grease and line the base of two 30 x 20cm baking trays with baking parchment.

2. Sift the cocoa powder into a mixing bowl, and pour in the butter, vanilla and water. Beat with a wooden spoon until you get a thick paste.

3. Separate the eggs and put the egg whites into a spotlessly clean glass mixing bowl. To be sure of no grease, you can wipe the bowl and electric mixer whisks with a little lemon juice or vinegar. Whisk up the egg whites until they form stiff peaks (i.e. when the whisk is lifted from the mixture, a peak forms that doesn't fall to one side). Add 50g of the caster sugar and whisk well until you have a glossy meringue. Set aside for a few minutes whilst you make the rest of the cake.

4. Place the egg yolks in a mixing bowl and add the remaining 100g of caster sugar. Whisk up the yolks/sugar for a few minutes, until the mixture has at least doubled in size, has become lighter in colour and is really frothy. (I whisked the egg whites before the yolks because I'm lazy and didn't want to wash the beaters in between).

5. Add the cocoa/butter paste to the egg yolks and whisk in until the mixture is an even brown colour.

6. Add a third of the egg whites/sugar (meringue) to the chocolate mixture and beat thoroughly with a large metal spoon.

7. Add the remaining meringue and gently fold this into the mixture. The egg whites are the only thing that allow the cake to rise so this needs to be done gently. Fold only until you can no longer see any egg whites.

8. Evenly distribute between the two trays, and tip the tray from side to side to get it to each corner. Bake for 12-15 minutes until springy to the touch and the cake is slightly coming away from the tray. Take out of the oven, and cover the trays with a damp tea towel until the sponges are completely cool.

9. Whilst cooling, make the buttercream by beating the butter until it is really soft and spreadable. Add half of the icing sugar and cream the butter into the icing sugar. Once all of the sugar has been added, add the other half of the icing sugar, the vanilla and 1-2 tbsp of milk, and beat until all of the sugar has been incorporated and the buttercream is thick enough to spread (but doesn't fly around the bowl when you stir it).

10. Once the cakes are cool, tip the sponges on two sheets of greaseproof paper. Remove the top layer of greaseproof paper carefully away from the sponge. To each short end of each sponge, lightly score a line across the sponge about 2cm in, along the length of the sponge.

11. Cover each sponge evenly with the buttercream. Scatter the top with blackberries.

12. To roll up the sponges, from the front short edge, roll up the cake, stopping in the middle. Repeat the same from the back until both rolls meet in the middle. Cut down the centre between the rolls.

13. Trim the ends of each sponge. Divide each sponge into three (they will be 6 cm in length). Transfer to a wire rack with the seam facing downwards. Place in the fridge for 15 minutes to set up.

14. Once ready to decorate, melt the milk and dark chocolate in a large microwavable bowl in the microwave on high power, stirring the chocolate every 30 seconds or so, until all of the chocolate has melted.

15. Place the wire rack onto a baking tray to catch the drips, and pour the chocolate over each sponge. Use a small palette knife to gently spread the chocolate over the sides of each roll, to cover the sides. This requires patience, and you can probably do a neater job than I did. It did finally work though :)

16. Set aside until the chocolate has firmed up.

17. Melt the white chocolate in a microwave on high power, checking every 15-20 seconds. Once the chocolate has melted, do something I didn't do, and wait for a minute until the chocolate becomes slightly thicker (to a consistency similar to what the milk/dark chocolate was once it was out of the microwave). I didn't do this so it was a little runny.

18. Pour the white chocolate into a piping bag, and snip off the end (about 1/2 cm up). Pipe lines across each mini roll. Leave to set.

19. Enjoy!