Preheat oven to 350ºF. Grease 3 6-inch pans brush with cake release place on a cookie sheet. Set aside.
Sift all the dry ingredients into a large bowl and make a well in the centre.
In a separate bowl, lightly whisk together all the wet ingredients, except puree.
Add the wet mixture to the dry ingredients and use a whisk to stir the batter. It will be thick.
Add the warm puree and continue to stir with the whisk until fully combined.
Divide the batter evenly into prepared cake pans.
Bake for 25-30 minutes on the cookie sheet on the middle rack of the oven. Rotate cookie sheet halfway through baking.
Remove from oven and allow to cool in pan for 10 minutes before turning them out onto a cooling rack.
Once completely cooled, level and torte cakes. You can brush the layers with some of the cherry/cointreau juices, like I did.
Make the gianduja buttercream:
Roughly chop the gianduja and add to a small bowl. Place the small bowl over a pot with simmering water to melt. Set aside to cool.
Using a clean towel and some lemon juice or vinegar, clean your mixing bowl, whisk attachment and utensils to remove any traces of grease.
Fill a heavy duty pot about a quarter of the way with water and place on the stove over medium heat to simmer.
Add egg whites, sugar and a pinch of salt to the bowl of a stand mixer and place over the pot of simmering water, ensuring the bottom of the bowl is not in contact with the water in the pot.
Whisk the sugar, egg white, salt mixture constantly, but gently, until temperature reaches 160°F.
Once at the correct temperature, remove from heat and dry the underside of the bowl with a towel before placing it on the stand mixer.
With the whisk attachment, begin to whip the meringue until it is thick, glossy, and the bottom of the bowl is no longer warm to the touch. Do not begin adding butter while the bowl is still warm.
With mixer on low speed, add butter cubes, one at a time, until incorporated. Continue to mix until it reaches a silky smooth texture.
Add the gianduja slowly, pouring in a constant stream, continuing to beat on low speed until well combined and silky smooth.
Assemble the cake:
Torte cakes and use a pastry brush, or spray bottle to soak the layers with the cherry/cointreau juice.
Smear a little buttercream on a cake board that is slightly larger than your cake. Place a layer onto the board and pipe a generous amount of buttercream onto the layer.
Repeat with another layer, until all layers are stacked. Ensure they are centred and level.
Crumb coat the cake, wrap with plastic wrap and place in the refrigerator for 15-30 minutes, depending on the temperature where you are.
Cover the sides and top of the cake with buttercream and use a spatula to spread and smooth the buttercream over the cake.
Fill a piping bag fitted with the French tip with remaining buttercream and pipe little dollops around the cake. Use a small offset spatula to randomly attach gold flakes. Enjoy!
Notes
When making meringue, ensure your bowls and utensils are grease-free by cleaning with lemon juice or vinegar. Any trace of grease will prevent the egg whites from reaching maximum volume. therefore ruining the meringue. :(Using a cake board that is slightly larger than your cake, provides a guide for applying an even coat of buttercream.