This gorgeous layered dessert features a brownie-like chocolate cake, luscious chocolate raspberry jam, and a light and fluffy raspberry and ruby chocolate mousse all enrobed in a stunningly shiny dark chocolate mirror glaze.
Yield: one 8-inch cake (about 12 servings)
Prep Time: 3 hourshours
Cook Time: 30 minutesminutes
Total Time: 3 daysdays
Ingredients
For Croustillant Base:
2ounces/ 56gdark chocolate, finely chopped
¼cup/ 74gNutella
¾cup/ 40gfeuilletine, or substitute puffed rice cereal, cornflakes, or crushed fortune cookies
For Chocolate Cake:
3.5ounces/ 100gdark chocolate, finely chopped
⅓cup/ 35gDutch-processed cocoa powder, sifted
2tablespoons/ 56gunsalted butter, cut into cubes
¼teaspoonespresso powder, omit if using coffee rather than water
In a bowl, gently melt chocolate, in short bursts at half power in the microwave, or over a double boiler. Once fully melted, mix in nutella, stirring until smooth, then fold in feuilletine until evenly coated and distributed.
Spread mixture onto a silicone or parchment-lined baking sheet, spreading it as thinly as possible in a roughly 8-inch round (it should be slightly larger than your the pan or ring you'll be using to assemble the cake). You can try spreading it directly into the bottom of your pan (if using a springform or removable bottom pan), but I find it's harder to get a thin even layer that way.
While the chocolate is still soft, use the cake ring to cut out a round that will fit perfectly into the bottom. You can also trace the bottom of your springform pan and then cut out the round with a knife (careful you don't cut through to your silicone mat).
Keeping the base flat on a cookie sheet, refrigerate until set and ready to use. This layer can be made ahead of time and refrigerated for a few days or even frozen for longer.
For Chocolate Cake Layer:
Preheat oven to 350 degrees F. Line an 8-by-8-inch baking pan with parchment paper.
In a bowl, combine chocolate, cocoa powder, espresso powder, and cubed butter. Pour boiling water over top, let sit for 30 seconds, then stir until chocolate and butter are fully melted. Set aside to cool to lukewarm.
In another bowl, whisk together flour, sugar, baking soda and salt and set aside.
To lukewarm chocolate mixture, whisk in egg and egg yolk, sour cream, and oil until smooth.
Pour into bowl with dry ingredients and stir until just incorporated and no streaks of dry ingredients remain.
Pour into prepared baking pan. Bake for 28 to 30 minutes or until a toothpick inserted near the center comes out mostly clean with a few moist crumbs attached (but no gooey batter). Place pan on a wire rack and let cool completely.
Optionally, you can compress the cake a bit as it cools, which will give it a flatter top and slightly denser texture. Lift out cake from pan and set on a wire cooling rack. Press a piece of lightly buttered or oiled parchment paper on top of the cake, then top with the square cake pan. Put a few things in the cake pan to weight it down slightly (maybe a pound or two of weight max, and space the weight evenly in the entire pan).
Once fully cooled, put the cake back into the baking pan, lightly cover, and freeze until ready to use, up to a month (if freezing for longer than a few days, you may want to wrap it tightly in plastic wrap and bag it to prevent freezer burn).
For Assembly:
When you're ready to assemble, prepare an 8-inch cake ring or an 8-by-3-inch round cake pan with removable bottom or a springform pan. Line sides with a 3-inch strip of acetate, securing in place with tape if necessary. If you are using a cake ring, set ring on a baking sheet lined with parchment paper or a silicone baking mat. You can also use a silicone cake pan/mold for this, no acetate needed (note the size difference though as it'll likely be smaller/shorter so you will need less mousse [**see notes]).
Place chilled croustillant base in the bottom of your prepared cake pan or inside your cake ring.
Remove cake from freezer and cut into a 6-inch round. You can use a 6-inch round cutter if you have one, otherwise trace the bottom of a smaller cake pan or other round object, and then cut carefully with a serrated knife. Place on top of croustillant base; whichever side feels stickier should go down.
Spread a thin layer of raspberry jam on top of cake, then put the whole thing in the freezer until your mousse is ready to go.
For Raspberry Mousse:
Cut gelatin sheets into 1-inch strips and submerge in cool water for at least 5 minutes to soften. If using powdered gelatin, sprinkle 3 teaspoons over 3 tablespoons of cool water to soften.
Place ruby chocolate in a large heat-proof bowl (the bowl should hold at least 2 quarts volume).
Puree raspberries in a blender or food processor, then strain through a fine mesh sieve, pushing out as much of the puree as you can. You should have about 3/4 cup or 200g of raspberry puree.
Transfer raspberry puree to a small saucepan. Add lemon juice and bring to a gentle simmer, stirring occasionally.
Remove from heat and add gelatin (if using leaf gelatin, squeeze out as much water as possible first) and whisk until gelatin is completely melted and smooth.
Pour still-warm raspberry puree over ruby chocolate. Gently whisk, starting in the center and working in small concentric circles, until a smooth and shiny emulsion forms, then gradually whisk in larger circles until all the liquid is completely incorporated and mixture is smooth. Set aside to cool for 5 to 10 minutes while you whip the cream (no longer or the gelatin will start to set).
In a clean bowl or the bowl of a stand mixer, beat heavy cream until it holds very soft peaks. Whisk in 1/3 of cream to the raspberry mixture to lighten, then add the rest of the cream and fold with a large rubber spatula until fully incorporated.
If desired, transfer some of the mousse to a piping bag or a plastic bag with 1-inch of the end cut off; I find it easier to get around the edges of the cake this way.
Pour or pipe mousse into cake pan or mold, taking care to spread it into all the corners and crannies around the cake. Fill to the very top of your mold then run a straight edge over the top to level; if it's not quite to the top, use a small offset spatula to get it as flat and smooth on top as you can. Tap it a few times against the counter to remove any air bubbles and even out the top surface.
Place entire assembly into the freezer and let freeze until completely firm, at least 6 hours or overnight if possible. Remove from mold or cake pan, peeling off acetate. Smooth out any rough spots with an offset spatula if necessary. Place on a baking pan or a cake board or and put back in the freezer until ready to glaze.
For Mirror Glaze:
Cut gelatin into 1-inch strips and submerge in cool water for at least 5 minutes to soften. Place chocolate in a heat-proof bowl and set aside.
Combine sugar, corn syrup, and water in a saucepan and bring to a boil over medium heat until sugar is completely dissolved and mixture is clear.
Remove from heat, then add gelatin (squeeze out as much water as possible first) and whisk until dissolved. Whisk in sweetened condensed milk followed by cocoa powder. Pour hot mixture over chopped chocolate and let sit for 30 seconds, then stir until chocolate is completely melted and mixture is smooth (stir gently to avoid air bubbles which are almost impossible to remove).
Let glaze cool, stirring occasionally, until glaze reaches approximately 95-98 degrees F on an instant-read thermometer. The glaze needs to be the correct temperature or it will not form a thick enough layer on the outside of the cakes. Mirror glaze can be made up to 5 days ahead of time; store in an airtight container in the refrigerator and rewarm in the microwave or a double boiler to ideal temperature before using.
Remove your cake from freezer and place on a wire rack set inside a cookie sheet, or elevated off the sheet using something slightly smaller in diameter than the cake itself so the glaze can drip off (the same 6-inch cake ring you used to cut the cake for example).
Pour glaze generously over cake until cake is completely covered. Allow the excess glaze to drip off for 5 or 10 minutes, then gently scrape the edges to remove any remaining drops or built up glaze. Carefully transfer cake to cake stand or serving plate and refrigerate until ready to serve.
Decorate with a mixture of fresh and crushed freeze-dried raspberries, plus a few flakes of gold leaf. If your bottom edge is a bit messy looking, you can do a border of fresh raspberries, chocolate curls, or sprinkles to finish it off.
For perfect slices, dip a large knife into hot water to warm it before slicing, and wipe off the blade completely between each cut. Glazed cake will keep uncovered in the refrigerator for up to 5 days.
Notes
* To substitute powdered gelatin, use 1 teaspoon of powdered gelatin for every 1 sheet of leaf gelatin called for in the recipe. Instead of softening the gelatin in cold water and then wringing it out, sprinkle the gelatin over a few tablespoons of cool water to allow it to soften, then add the whole mixture to the hot liquid to dissolve.
**If you’re using a smaller silicone cake mold, or if you’re using a pan or mold that’s only 2 inches tall instead of 3, you can reduce the quantity of the mousse by a third (multiply all quantities by .66—so use 200g ruby chocolate, 1 1/2 cups heavy cream, and so forth). The other portions of the recipe are fine as is.
***Mirror glaze can be made up to 5 days ahead of time or frozen for even longer; rewarm in the microwave or double boiler until fully melted and smooth, then let cool to ideal temperature before using. This recipe makes enough glaze for two full cakes, but I always like to have more than enough glaze to ensure an even coat.