Angel Food Layer Cake with Lemon and Lime Curd, Saffron Italian Meringue Frosting and Passionfruit

It was my husbands birthday last week, so I made him this cake.  I'm cool like that.

Angel Food Layer Cake with Lemon and Lime Curd, Saffron Italian Meringue Frosting and Passionfruit

Slightly adapted from here

For the Curd:

Zest of 2 lemons

Juice of 1 lemon

Zest of 2 limes, plus their juice

3 eggs, lightly beaten

100g unsalted butter, chopped

200g caster sugar

For the Cake:

10 egg whites, at room teperature

1 teaspoon baking powder

Pinch of sea salt

1 tablespoon white vinegar

425g caster sugar

1 tablespoon vanilla sugar

175g plain flour

For the Frosting:

250g caster sugar

5 egg whites

Pinch sea salt

3 drops lemon juice

1 teaspoon saffron threads soaked in 100ml boiling water for about 10 minutes

For the Topping:

Flesh of 3 - 4 passionfruit

Make the Curd:

Put the zest of both fruits and their juices into a heatproof bowl.  Add the eggs, butter and sugar and place the bowl over a pan of simmering water, without letting the bowl touch the water.  Cook, stirring occasionally, for about 20 minutes or until smooth and thickened.  Leave to cool, then chill for a few hours in the refrigerator to set.  I usually do this the day before I want to use/eat it.

Make the Cake:

Preheat the icing to 175C.  Very lightly butter a 20cm (measured from the base) angel food cake pan.  Set aside.

In the clean and dry bowl of an electric mixer fitted with the whisk attachment, whip the egg whites until soft peaks.  Mix the baking powder, salt and vinegar together in a small bowl and add it to the whipped egg whites while the mixer is still going.  Add 300g of the caster sugar and all of the vanilla sugar, a tablespoonful at a time, while continuously whisking.  Once all the sugar has been incorporated.  stop the mixture and sift the flour and remaining 125g of caster sugar over the mixture and fold it in with a spatula.  

Spoon the batter into the prepared pan and bake for 35 minutes, until golden on top.  Don't open the oven door during baking.

Leave the cake in the pan and set on a wire rack to cool for 10 minutes before turning the cake over on the rack.  Leave the up-turned cake until it releases from the sides itself  Leave to cool completely.

Make the Frosting:

Drain the water from the saffron threads, discard the saffron.  Put the saffron water and sugar into a small saucepan and bring it to a boil.  Boil until the temperature reaches 121C on a candy thermometer.

In the meantime, in the clean and dry bowl of an electric mixer fitted with the whisk attachment, whip the egg whites with the salt until soft peaks.  Add the lemon juice.  Continue whisking as you gradually add the hot sugar syrup in a thin stream.  Keep whisking until the mixture has cooled, about 10 minutes.

Assemble the Cake: 

Cut the cake horizontally into thirds.  Put the bottom layer of cake on a cake stand lined with pieces of baking paper (so that you can catch any drips and keep the stand clean).  Spoon half of the lemon and lime curd on and spread around evenly.  Top with the middle layer of cake and spread it with the remaining curd.  Place the final layer of cake on top and cover the entire cake (top, sides and down the center hole) with a generous layer of frosting.  Scoop the flesh out of the passionfruit and use it to adorn and perfume the top of the cake.  Remove the paper from under the edges of the cake, stand back, admire your work of art, then dig in.