Raspberry Mousse Cake

This rich chocolate cake, with its fluffy raspberry mousse, thin chocolate mirror glaze, fresh raspberries and crunchy chocolate bits is truly a cake that makes a statement! It’s easier than it looks, but you will need to start it the day before you serve it as it needs to set overnight.

Raspberry Mousse Cake

Servings: 8-10
Time: Cake: 1 hour, Mousse: 40 minutes + overnight freeze, Mirror Glaze: 20 minutes
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Chocolate Cake
1-1/2 cups (319 g) light brown sugar
1-1/2 cups (180 g) unbleached flour
1/2 cup (61 g) Dutch process cocoa
1-1/2 tsp (6 g) baking soda
3/4 tsp (3 g) baking powder
Pinch of salt
3/4 cup (179 g) strong coffee
3/4 cup (169 g) buttermilk
1/2 cup minus 2 tsp (89 g) vegetable oil
2 large eggs (115 g)
1 tsp (4 g) vanilla extract

Preheat oven to 350°F. Prepare two 8″ cake pans with oiled parchment cut to fit the bottom of the pans. Set aside.

Combine sugar, flour, cocoa, baking powder, soda and salt in the bowl of a mixer and whisk on low to combine, making sure it’s lump free. Add the coffee, buttermilk, oil, eggs and vanilla and mix on medium low for two minutes, stopping to scrape down the sides. The batter will be pourable.

Divide the batter among the prepared pans and bake for 15 minutes, until an inserted toothpick comes out clean. Let the cakes cool before removing them from the pans and cool completely on a wire rack. Remove parchment papers before assembling.

The cake layers can be wrapped in Saran wrap and refrigerated for up to two days in advance until ready to frost.

Raspberry Mousse
3/4 cup raspberry puree (restaurant supply stores have this)
OR
Make your own:
12 oz or 340 g bag of frozen raspberries
1/2 cup (100 g) sugar
1/2 tsp freshly squeezed lemon juice

2 T fresh lemon juice
1 T Knox unflavored gelatin
2 cups heavy whipping cream
3 T powdered sugar

To make your own raspberry puree:
Place frozen raspberries, sugar and lemon juice in a small saucepan and cook on a gentle simmer until sugar has dissolved, the raspberries have released their juice and sauce has thickened slightly.

Whether you make your own puree or buy it that way, you’ll want to strain the raspberry sauce through a fine mesh sieve at this point, pressing the raspberries down to extract as much juice as possible. Don’t worry if a few seeds get through!

Pour the juice back into the saucepan. Whisk in the 2 T of fresh lemon juice and the unflavored gelatin and put back over low heat just until the gelatin is dissolved into the raspberry sauce. Refrigerate the raspberry sauce until it’s room temperature (around 70°F / 21°C). Be careful not to leave it in the fridge too long as the gelatin will start to set quickly.

Whip the heavy whipping cream to soft peaks. Add powdered sugar and continue beating until firm peaks form. Refrigerate until ready to use.

Once the raspberry sauce is cooled to room temperature, fold the raspberry sauce into the whipped cream, a little at a time.

Assembling the Cake
Once you’ve mixed the mousse evenly, spread 1/4 of the mousse evenly over the first cake layer and top with the second layer of cake. Spread another 1/4 of the mousse over the top.

The key to getting an even layer of mousse on the sides is to lay a 9″ ring or 9″ springform pan over the 8″ cake

Piping is the easiest way to do this, but you can also spoon the mousse in too

Center the cake on a flat 10” cake circle. Take a 9” spring form pan and place it around the cake (there should 1/2” between the cake the edge of the ring all around).

Spoon the remaining mousse into a piping bag (no piping tip necessary). {A gallon size plastic bag serves in a pinch too). When you’re ready, cut off an inch or so off the end (or corner) of the bag and pipe the mousse into that 1/2” space around the cake. (You can also use a spoon to do this if you don’t have a bag).

Using a cake spreader (or a long knife), make sure the mousse fills the space completely and then scrape along the top of the ring so it is smooth and even. Cover it with plastic wrap and place it in the freezer overnight.

Dark Chocolate Mirror Glaze
I like to make this a day ahead, as it needs time to set before using.

1 cup (206 g) granulated sugar
Scant 2/3 cup (142g) heavy cream
4 tsp (12g) powdered gelatin
1/4 cup (60 g) cold water
2/3 cup (148 g) room temperature water
1/2 cup + 1 tsp (71 g) cocoa powder

In a small bowl, dissolve the gelatin in the cold water.

In a medium pot, bring sugar and heavy cream to a boil over medium heat, stirring until the sugar dissolves.

In a medium bowl, combine the room temperature water with the cocoa powder, stirring with a spatula until it becomes a uniform paste.

Stir the bloomed gelatin into the cream-sugar mixture until dissolved, then stir in the cocoa powder paste until combined. Remove the pot from the heat, and pour the glaze mixture through a mesh strainer over a heatproof bowl to remove any clumps of undissolved cocoa powder. Emulsify the mixture with a hand blender to remove any lumps, until smooth.

Cover and chill in the fridge overnight to set, until ready to use. You can store in the fridge in an airtight container for up to 1 week.

When you’re ready to glaze your cake, remove the glaze from the fridge and heat in the microwave until it’s between 90°F and 94°F (32 to 35°C), so it’s liquid and pourable and will give your cake a shiny, uniform finish. If it looks like it’s slightly separated, use a hand blender to blitz it together. Make sure to tap the container a bit so that the bubbles from blending go away.

Preparing for the Glaze
The next day, (or long enough later that the cake is frozen completely solid), remove the cake from the freezer. Remove the springform ring (heating the sides for a few seconds with a culinary torch makes for easy release). You can use warm clean fingers to fix any small blemishes at this point. The goal is to have the top and sides be as smooth as possible.

Before you put your springform pan in the freezer, scrape along the top so that it is even.

Remove the springform outside by using a culinary torch for a quick second all the way around. You can also wet a hand towel with hot water, squeeze it out and lay it on the metal

Remove the cake from its cardboard bottom and set it on a 6″ cake pan (I like using 32 oz tomato cans. Just use any container that is smaller than the 8″ round cake size and stable enough to hold its weight). Center both on top of a rack over a clean sheet pan or cookie sheet. Make sure the pan is clean because you can reuse extra glaze.

Glaze pouring should be fast and even. Resist the temptation to make it too thick.

Have a clean toothpick at the ready to pop any bubbles right after pouring.

Pouring the Glaze
Pour the mirror glaze over the frozen cake in a smooth, continuous pour over the top of the cake until it starts running down the sides. Don’t be too heavy handed with it as it tends to get a rubbery texture if the glaze is too thick. Be fast with any touch ups! Have a toothpick ready to pop any bubbles before they set.

Once the glaze has set (10 minutes or so), you can trim the drips away with scissors at the base. Place the cake on a larger cake board or platter.

Do not freeze once the glaze has been put on, but do keep it chilled in the fridge for a few hours so that it defrosts before slicing and serving.

Decorations
Try dipping a dry basting brush into some raspberry luster dust and flick it gently on the top of the cake before it dries. Add chocolate shavings along the base, and you can also place chocolate accents or place fresh raspberries for special effect.