Six different colored layers alternating with a vanilla-flavored yogurt cream filling and frosting… the rainbow cake is perfect for any special occasion! Find this and many more recipes with pictures on the English version of the Giallozafferano App http://itunes.apple.com/app/giallozafferano-recipes/id384387249?mt=8
Firstly, prepare the yogurt cream filling because it needs to set in the fridge, so fill a bowl with cold water and soak the gelatin leaves: cut them in half to ensure they are fully covered; it takes about 10 minutes. While the gelatin is soaking, heat the heavy cream until hot, about ½ cup (100 ml), and turn off the heat: once the gelatin is soft, squeeze and let it melt into the cream. Meanwhile whip the remaining cream, cold from the fridge, add the sifted powdered sugar and the seeds from a vanilla pod. And now a little trick to prevent staining… I’m ready! The leaf gelatin should be soft by now, so drain and add to the warm cream… it’s already melted! Allow to cool a bit, then transfer to a cold bowl. Now beat the Greek yogurt until softened. Add the gelatin mixture to the whipped cream and stir gently until blended. Now fold in the Greek yogurt. The yogurt cream filling is ready to cool: transfer to an oven dish, to cool quickly; cover with cling film, touching the surface, and place in the fridge to set for at least 2 hours.
Next, make the batter for the rainbow cake: separate the egg yolks from the whites; add the seeds from a vanilla pod, the honey and half of the sugar to the egg yolks, and beat the egg whites with the other half of the sugar. The egg whites should be at room temperature for best results. Divide the sugar into equal parts, and use half for the egg yolks and half for the egg whites, as said before. Beat the egg yolks until pale and fluffy – it takes about 10 minutes – then pour in the heavy cream and stir gently; transfer to another bowl, large enough to hold the egg whites as well. Beat the egg whites until soft peaks form, not stiff peaks; they are still creamy as you can see!
Now sift in the flour and baking powder: this is not a standard sponge cake but a sponge cake roll – typically used for Swiss rolls – and it’s baked at a higher temperature. Fold gently, without deflating the mixture, then divide the resulting batter equally into 6 bowls: 6 bowls for 6 different colours. I’m using red, yellow, orange, blue, green and purple. Wear gloves to avoid staining your hands and start with the first batter: take a small bowl, add a few drops of water and mix in the food coloring. Add the mixture to the batter and incorporate with a spatula until you get the desired colour. I’m using paste or gel food colorings, but also powdered food colorings produce a bright result. Here’s the first colour, repeat with the others.
Perfect, now it’s time to bake: a baking tray, or a shallow baking pan, lined with parchment paper, and a ring mould, 7 inches (18 cm) in diameter – otherwise use a round baking pan; pour in the batter and bake in a preheated static oven at 390°F (200°C) for 9-10 minutes: test for doneness after 9 minutes, to avoid excessive browning.
The cake layers are baked and cooled. Now alternate with the yogurt cream filling, that has been blended in a food processor to remove any lumps; put two thirds in a pastry bag with a plain tip of about ½ inch (1 cm) and leave one third covered in the fridge, to use for decorating. Start with the red layer: place on a serving platter and add the filling, in this way. Repeat until all the cake layers are used up. Remove the reserved yogurt cream filling from the fridge and frost the whole cake, a rotating cake stand is very useful here: take a spatula and coat the sides. You can further decorate the cake with rosettes of yogurt cream, but first place in the fridge to set. Meanwhile let’s see together the ingredients needed for this recipe!
For the yogurt cream filling
- 6 ¼ cups (1250 g) of Greek yogurt
- 2 cups (500 ml) of heavy cream
- 1 ½ cups (170 g) of vanilla powdered sugar
- 1 vanilla pod
- 1,5 oz (40 g) of gelatin leaves
For the cake layers
- 10 medium eggs
- 1 cup (250 ml) of heavy cream
- 1 ½ tbsp (30 g) of honey
- 2 ½ cups (300 g) of cake flour
- just over 2 cups (420 g) of sugar
- 1 vanilla pod
- 2 ⅔ tsp (12 g) of baking powder
- powdered, paste or gel food colorings: red, orange, yellow, green, blue, purple