If you are obsessed with mirror glazed cakes, perhaps you’ve heard of the absolute goddess of the mirror universe, Ksenia Penkina. The stuff she does is purely mind-blowing. Ksenia offers classes online and for a long time I dreamed about taking one. I finally caved and got her introductory class, in which she explained how to make this adorable mousse cake. Having changed quite a few things in the recipe, (cake base, insert and glaze), I feel it’s ok to share. Plus, it would be impossible to offer in a blog post everything you get from watching her. Running no risk of infringing any copyright issues, I show you two versions of the same mousse cake, a larger one in a traditional format, and a small cake that would be perfect for a Valentine’s Day dessert. They were both made to celebrate Aritri’s PhD defense in November, a wonderful accomplishment by our most amazing graduate student. Congratulations, Dr. Majumdar!
WHITE CHOCOLATE RASPBERRY MOUSSE CAKE
(adapted from Ksenia Penkina)
for the hazelnut dacquoise:
120 g ground hazelnuts (peeled and lightly roasted)
135 g powdered sugar
40 g all-purpose flour
200 g egg whites, at room temperature
pinch of cream of tartar
70 g granulated sugar
for the raspberry insert:
7.5 g gelatin (around 200 bloom)
40 g cold water
280 g raspberry puree, sieved to remove seeds
12 g cornstarch
80 g sugar
for the white chocolate mousse:
11 g gelatin (200 bloom)
60 g cold water
350 + 400 g heavy cream (divided)
370 g white chocolate, finely diced
30 g fresh lemon juice
for the mirror glaze (adapted from Phil’s Home Kitchen):
2½ sheets (4g) of Platinum grade sheet gelatine
150 g liquid glucose
150 g granulated or caster sugar
100 g condensed milk
150 g white chocolate, chopped fairly small
1/2 tsp titanium oxide
red, black, pink and white gel food colouring
tempered white chocolate for decoration (optional)
sprinkles for decoration (optional)
Prepare a 7 inch cake ring by wrapping it in plastic from the bottom to the sides, so you can use it to pour the fruit insert and freeze it later. Make sure it is sitting on a flat baking sheet that will fit in your freezer.
Heat the oven to 350 F.
Make the dacquoise base: in a bowl, mix together the flour, powdered sugar, and ground hazelnuts. Reserve. Make a meringue by whisking the egg whites with the cream of tartar until very foamy. Add the sugar slowly, whisking in high-speed until soft peaks form. Delicately fold the dry ingredients into the meringue. Spread as homogeneously as possible in a baking sheet to have a thickness of about 0.4 inch (1 cm). Bake for 15 to 20 minutes. Cool it completely and store in the fridge until ready to assemble the cake.
Make the raspberry insert: In a small bowl, add the cold water, then pour the gelatin powder on the surface, gently mixing to hydrate the powder. Let it sit at room temperature for 10 minutes. Sift the sugar with the cornstarch and add to the puree of raspberries in a saucepan. Bring to a boil, stirring constantly. Turn the heat off, allow the mixture to cool to around 175 F (80 C), and add the bloomed gelatin, whisking well to fully incorporate it into the hot liquid. Pour some of it in the prepared cake ring to a depth of 1/2 to 3/4 inch. If using the heart-shaped mold, pour an amount to give similar thickness into that pan too. You will use the full amount made to divide in the two pans. Freeze for several hours, or preferably overnight.
Make the white chocolate mousse: mix the gelatin with water as described for raspberry insert. Reserve. Heat 350 g of heavy cream in a saucepan until bubbles appear around the edges. Pour over the white chocolate, add the bloomed gelatin, stir gently until chocolate is dissolved. Warm the lemon juice briefly in the microwave, and pour over the white chocolate cream. Reserve.
Whip the remaining 400 g of heavy cream until it reaches the consistency of melted ice cream. Fold gently into the reserved white chocolate mixture. Your mousse is done.
Assemble the cake: remove the pans with the frozen inserts from the freezer and remove them from the molds. Prepare a slightly larger cake ring (8 inch) with plastic wrap in the bottom to assemble the larger cake. Add to the bottom of each pan (cake ring and heart-shaped mold) a layer of white chocolate mousse. Carefully place each insert floating on top, trying to center them as well as possible. Cover the mold almost to the top with mousse, then add the reserved dacquoise on top. Fill and gaps on the sides with mousse to make a smooth top (which will be the bottom of your un-molded dessert). Freeze overnight. Really important that the cake is absolutely frozen before proceeding with the glaze.
Make the mirror glaze. Put the water, sugar and liquid glucose in a small pan and bring to simmering point, stirring occasionally to dissolve the sugar. Remove from the heat and let it stand for about 5 minutes. This is the base syrup for the glaze. Meanwhile, soak the gelatin in some cold water for about 5 minutes. Squeeze out the excess water and stir into the hot water, sugar and liquid glucose mixture to dissolve. Stir in the condensed milk.
Put the chocolate in a medium bowl and pour this hot mixture slowly over the chocolate, stirring gently to melt it, avoid making bubbles. A stick immersion blender works great, but you must keep the blades fully submerged at all times. If bubbles are present, pass the mixture through a fine sieve. Add 1/2 tsp titanium oxide to the mixture, divide in two portions. You are aiming for two different tones of red. I used red and a tiny amount of black dye for the darker color, red, pink and white to the second portion.
Leave the glaze uncovered for an hour at room temperature for the glaze to cooled and be slightly thickened: if it is too runny you will get too thin a layer on top, colors will not blend well and less glaze will cling to the sides of the cake. The ideal temperature to pour the glaze is 92 to 94 F. Once it is slightly above that (around 97 F), pour both colors in the same container, barely mix them, and pour over the frozen, un-molded cakes sitting over a rack with a baking sheet underneath.
Tap the rack gently to settle the glaze, and very gently and quickly run an off-set spatula on top of the cake to force excess glaze to run down the sides. Do that just once, or you will ruin the marble effect. Drips under the cake can be cleaned with a spatula or sharp knife. Let the glaze set at room temperature for 15 minutes, add the decorations of choice, then place the cakes in the fridge for 2 to 3 hours. Use a hot knife to cut slices without compromising the glaze.
to print the recipe, click here
Comments: The recipe will make two cakes, you can definitely cut it in half and bake a single large cake or a couple of small ones. I used a Silikomart mold called Amore for the small cake, and a cake ring, 8 inch diameter for the large one. The original cake base was a coconut dacquoise, but Aritri is not too wild about coconut in desserts, so I used a hazelnut version instead. Ksenia has access to a different type of gelatin, hard to find in the US, so I decided to stick to the mirror glaze formula from Philip’s blog, as I’ve been doing lately.
The larger cake was glazed a few hours before the heart cake, so I could only do the two-color effect on the big one. The leftover glaze was saved and applied to the small cake, but then the colors were obviously mixed. To add a bit more of a festive look, I used decorations from Fancy Sprinkles, a company I advise you to visit with restraint. Dangerous, very dangerous site. You’ve been warned.
To decorate the larger cake, I sat in front of a candle in a comfortable Full Lotus posture (yeah, right), went through 113 cycles of deep breathing, and… tried my hands at tempering some white chocolate. Against all odds, it was successful. Once I was done with my extended version of the Ecstatic Dance, I piped random crisscrossed lines on acetate film, let them set, broke them into small pieces and attached them to the base of the cake. In retrospect, I should have planned the decorations more carefully to come up with something a little more elegant. But truth be told, tempering chocolate is so tricky for me, I never expect it to work. When I realized it was all good, I had no specific plan on how to use it. Oh, well. Next time I’ll be ready. And then we all know what might happen: both chocolate and me will lose temper. Story of my life.
The cake tasted pretty amazing. I do think the combination of raspberries with white chocolate is hard to beat. Raspberries shine in desserts because they have such tangy flavor, cutting through excessive sweetness. The hazelnut dacquoise retained its nice texture during the freezing-thawing process, it did not turn mushy at all. I need to fine tune the amount of gelatin in the glaze, though. It seems a tad too runny.
One of the tricky parts of this type of dessert is baking a very uniform layer of cake or biscuit base. For cookie type bases (sable for instance), you can roll the dough using plastic guides with specific dimension. For cakes like dacquoise or genoise, I think baking frames could be the best option. Must investigate. Could be a fun gadget to showcase in a future “In My Kitchen.” The sacrifices one makes in the name of blogging!
As far as mousse cakes are concerned, this is a reasonably simple one, because it involves a single mousse, a single insert, and a single layer of cake/biscuit. If you are worried about making a mirror glaze, the cake could be served “naked” with some simple decorations on top. A drizzle of milk and white chocolate, a drizzle of white chocolate with some red dye dissolved in it, sprinkles, shaving of tempered chocolate, so many things you can do. But between you and me, the mirror glaze just makes a simple cake super special. Perfect to celebrate a terrific PhD defense!
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