''For the July Daring Baker’s Challenge, Ruth from The Crafts of Mommyhood challenged us to bake a cake. But not just any cake; she asked us to add in a special surprise for our eyes as well as our taste buds!''
Plain chiffon sponge cake
3 egg whites
3 egg yolks
150gr cake flour
150gr granulated sugar
6gr baking powder
as preferred vanilla
Chocolate chiffon sponge cake
as in plain chiffon with the substitution of 32gr flour with cocoa powder
170gr butter, room temperature
50gr shortening, room temperature
3 egg whites, room temperature
100gr granulated sugar
as preferred vanilla
60gr hazelnut praline (caramelised hazelnuts)
75gr dark chocolate, melted
rest of the buttercream
40ml hazelnut liqueur
200gr simple syrup
For the chiffon sponges mix the ingredients for each flavor in separate bowls excluding the egg whites and 50gr of sugar from each recipe. Whisk the mixtures for about 3min and separately beat the egg whites and sugar to meringue. Then fold half of the meringue in each mixture and fill two 20cm-diameter rings sealed on the bottom with aluminum foil. Bake at 170C for about 45min, let cool and preferably refrigerate before cutting. Continue with the buttercream by thoroughly mixing the butter with shortening. Then combine the sugar with glucose and water in a small pot and keep watching the temperature with a candy thermometer until it reaches 100C.
At this point start whisking the egg whites at high speed . When they become foamy and the syrup reaches soft ball stage at 120C, remove from heat and pour the syrup into the whites in the form of a string dripping between the bowl and the whisk, while whisking in medium speed. Continue beating at high speed until cool. Making sure that the meringue is not warm enough to melt the butter, gradually whisk it in also adding the vanilla. If necessary soften the hazelnut praline with some liqeuer to get a foldable consistency and combine it with 240gr of the buttercream. In the rest of the buttercream fold the melted chocolate with the last quite cooled down.
Cut each sponge cake in four layers keeping three from the one and 2-3 from the other. If you choose the chocolate one as the first, place one layer on the bottom and brush with the mixture of liqeuer and simple syrup. Then spread a layer of hazelnut buttercream 3mm thick and cover with a plain sponge layer also moistened with syrup. Spread hazelnut buttercream and repeat the same process ending up with a plain chiffon on top. After refrigerating for a couple of hours, take a sharp pointy knife and insert it diagonally 2cm from the sides of the top and towards the bottom at a distance of 8cm from the periphery.
Cut all way parallel to the perimeter and remove a cone shaped piece with two bases measuring 16 and 4cm. Set aside and spread a layer of chocolate buttercream on the remaining cake, placing a chocolate sponge on top. Moisten with syrup and push the layer down to make sure it touches the sides of the hole beneath. Then turn the cake upside down and push down the sides to invert the shape of the hole. Spread another layer of chocolate buttercream and replace the cone in the hole. Optionally cover with chocolate buttercream and another sponge on top or just finish by frosting the cake with leftovers of the filling.