I made this cake over the course of three days, and I highly recommend breaking it up like that to make your life easier! I baked the cakes on day 1, then made the ganache, raspberry filling, and raspberry frosting and filled and frosted on day 2, and finally, made the chocolate glaze and decorated the cake on day 3. This worked pretty well for me, although day 2 was a little long. It was totally worth it in the long run, though, as the birthday girl LOVED the cake and said it was the best one she had ever had! Everyone was ooooh-ing and ahhhh-ing over the presentation, too--it looks very professional, but it's actually pretty simple! But enough preamble...on to the recipe!
Chocolate Raspberry Truffle Cake (very slightly adapted from Annie's Eats)
For the cake:
- 1 1/2 c. unsweetened cocoa powder
- 1 Tbl. instant coffee granules
- 1 1/2 c. boiling water
- 3/4 c. sour cream
- 1 Tbl. vanilla extract
- 3 sticks (12 oz.) unsalted butter, at room temperature
- 2 1/2 c. plus 2 Tbl. sugar
- 3 large eggs
- 1 3/4 c. plus 2 Tbl. all-purpose flour
- 1 1/4 tsp. baking soda
- 3/4 tsp. salt
Cream together butter and sugar until light and fluffy. Beat in eggs, one at a time, and vanilla. Meanwhile, sift together the flour, baking soda, and salt. Add the dry ingredients to the butter/sugar mixture in three additions, alternating with the cocoa/sour cream mixture. Mix each addition until just combined.
Divide the batter evenly into three buttered and cocoa-powdered (won't leave your chocolate cake white like flour would) 9" round cake pans. Bake at 350 degrees F for 35 minutes, or until a toothpick inserted into the center comes out clean.
Let cakes cool for 15 minutes in the pans, then remove them from the pans and transfer to wire racks to cool completely. Once cool, level the cakes using a serrated knife.
For the raspberry filling:
- 16 oz. frozen raspberries, thawed
- Up to 1 1/4 c. raspberry wine, as needed
- 1/3 c. sugar
- 3 Tbl. cornstarch
- 1 tsp. lemon juice
Put the sugar and cornstarch in a medium saucepan, whisking to combine them. Transfer the raspberry liquid to the saucepan slowly, whisking it into the cornstarch so that it doesn't clump up. Heat over medium-high heat, whisking occasionally, until mixture boils and thickens. Remove from the heat, whisk in the lemon juice, and fold in the raspberries.
Cover and chill until you're ready to use it.
For the ganache filling:
- 8 oz. semisweet chocolate chips
- 1 c. heavy cream
- 3 Tbl. unsalted butter, at room temperature
Combine chocolate chips and heavy cream in a microwave-safe bowl. Microwave in 30-second increments, stirring in between each one, until chips have melted. Whisk in the butter, 1 Tbl. at a time.
Transfer 1/2 c. ganache to a piping bag fitted with a star tip and another 1/2 c. to a piping bag fitted with a plain tip. Let all the ganache cool until thickened but still soft enough to spread and pipe.
For the raspberry frosting:
- 1 c. sugar
- 4 large egg whites
- 21 Tbl. unsalted butter, at room temperature
- 1/3 c. strained raspberry puree (just puree fresh raspberries and strain!)
- 1/2 tsp. vanilla extract
Combine sugar and egg whites in a heatproof bowl set over a pan of simmering water. Cook, whisking constantly, until sugar dissolves (it shouldn't feel grainy when you rub the egg whites between your fingers) or until egg whites reach 160 degrees F. Remove from heat, and whip egg whites until the mixture has cooled to room temperature and the egg whites have reached stiff peaks, about 8 minutes.
Add the butter, 2 Tbl. at a time, whisking until each addition is incorporated. If it looks curdled, just keep beating--it will come together! Once all the butter has been added and the frosting is thick and creamy, beat in the raspberry puree and vanilla extract.
For the chocolate glaze:
- 4 oz. semisweet chocolate chips
- 1/2 c. heavy whipping cream
- 1/4 c. light corn syrup
- 2 tsp. vanilla extract
Combine chocolate and heavy cream in a microwave safe bowl--if you have a Pyrex measuring cup that is big enough, use that to save yourself an extra step! Microwave at 30-second intervals, stirring in between each one, until chocolate is melted. Stir in corn syrup and vanilla extract. Transfer to a pitcher or measuring cup with a spout.
Take one of your cooled, leveled cake layers, and put it on a cake board. Spread with approximately half of the chocolate ganache that's still in the bowl. Take the chocolate ganache in the plain-tipped piping bag, and pipe a border around the edge of the cake--this will help hold in the raspberry filling. Spread approximately half of the raspberry filling inside this ganache border.
Top with your second cooled, leveled cake layer. Repeat the process with the rest of the ganache and raspberry filling. Top with the third cake layer--put this one upside down so that the clean edges from the bottom of the pan are on top! This is a good point to refrigerate the cake to let the chocolate and raspberry fillings set up before frosting the cake.
Frost the entire cake with the raspberry buttercream, starting with the top and working the frosting down around the edges. Make the sides as smooth as possible! This is another great point to stop and refrigerate the cake to set the frosting before proceeding on to the next step.
Lastly, take the chocolate glaze, and pour it slowly over the top of the cake, making sure that it covers the entire top and just starts to drip down the sides. Refrigerate the cake for a while to let the glaze set.
Finally, take the ganache in the star-tipped piping bag, and pipe little swirls or rosettes around the top of the cake. Top each one with a fresh raspberry.
Pray to every god you can think of while transporting this cake that you've spent 3 days on to its destination. Glare at anyone who gets too close to the cake before the birthday girl has seen it in its pristine state. Revel in the delight in her eyes. Devour. :)