Golden Cube – Pistachio Petit Gateaux with Passionfruit Jelly and Milk Chocolate Coating

This indulgent Golden Cube is a dream come true (edible tho)- it has a nutty pistachio bavarois mousse, tangy sweet passionfruit jelly, and fluffy sponge, all covered with a layer of smooth milk chocolate coating dusted with gold powder. 

After my school has officially finished, I recently went back home to relax and recharge myself before the commencement of my industry placement. I didn’t really bake much back home due to limited resources so I was so ready to storm the kitchen as soon as I am back in Sydney! In case you’re wondering, I will be working full-time for six months at Baked by Keiran, an Artisan Bakery/Patisserie in Dulwich Hill, Sydney. I have been working there part time for over a month now and I simply enjoy every moment of it despite the early hours. I guess getting up earlier than everyone else is just an inevitable part of being a pastry chef, right? Anyway, working there substantially equips me with knowledge about French patisserie as they make almost everything from scratch, which I absolutely respect. 

Back to the dessert itself, pistachio is my second favourite flavour (right behind mint chocolate) because of its unique exotic, nutty, sweet taste. To be honest, I don’t even know how to describe the taste of pistachio to do it justice. I personally think that the combination of pistachio and milk chocolate works well, because the creamy and milky note of milk chocolate complements the delicate flavour of pistachio. And the acidity of passionfruit jelly insert perfectly balances out the sweetness of other elements.

Making this kind of dessert, like many other instances in the pastry world indeed, requires a lot of patience because it requires a lot of chilling time for things to set properly in the freezer. Sometimes you simply can’t rush things to go quicker because you will risk ruining everything. Make sure you plan everything ahead so that you will have enough time to finish the product. When I made this, I also tried to multitask by making another dessert at once so I don’t get bored with the waiting time. Hope you enjoy the recipe. Cheers! 

The specific tools that I used for this recipe include:

1. 15cm cake ring 
2. 4cm circular cutter 
3. 4cm half sphere silicone mould
4. 5cm cube silicone mould 
5. Toothpick 

Ingredients:

Sponge

• 4 egg yolks
• 45ml full-cream milk
• 40g melted butter 
• 4 egg white
• 100g sugar 
• 110g cake flour, sifted 
• 1/2 tsp baking powder 

Passionfruit Jelly

• 170g passionfruit pulp
• 100ml warm water 
• 4 tsp gelatine powder 
• 100ml cold water (for blooming the gelatine powder)

Pistachio Bavarois

• 100g egg yolk
• 80g caster sugar 
• 240ml milk
• 240ml cream
• 1 tsp vanilla extract
• 100g pistachio paste 
• 2 tsp gelatine powder 
• 50ml cold water (for blooming the gelatine powder)
• 400 pure cream, semi-whipped 

Milk Chocolate Pistachio Coating 

• 400g milk chocolate
• 80g vegetable oil (I used canola oil) 
• 80g shelled pistachio, coarsely chopped 

Instructions:

Sponge

1. Grease and line a 15-cm cake ring and set aside.
2. Preheat oven to 175C.
3. In a mixing bowl, combine egg yolks, milk and melted butter with a whisk.
4. Prepare sifted cake flour and baking powder in another bowl and set aside.
5. Using an electric mixer with a whisk attachment, whisk egg white on medium speed until foamy, then turn to high speed while slowly adding sugar. Continue whisking until the meringue reaches stiff peak.
6. With a spatula, gently fold in the prepared cake flour and baking powder into the meringue. Try to retain as much air as you can while folding.
7. Take out a little bit of meringue mixture and mix it with the egg yolk-butter mixture that you prepared earlier. Then fold it back to the whole meringue mixture. Gently mix with a spatula until everything is combined.
8. Pour the cake batter into the prepared cake mould. Bake at 175C for 35-40 mins, or until stick inserted into centre comes out clean.
9. Leave it in room temperature for 10 mins before handling. Take the cake from the cake mould and let cool completely. Using a serrated knife, cut the cake into 1-cm slices and put in freezer for 15 mins to firm up. You will need to use the slices from the middle part because they are softer and don’t have the skin.
10. Using a 4-cm circular cutter, cut out 10 sponge circles from the cake slices for assembly.

Passionfruit Jelly

1. Prepare a 4cm half-sphere silicone mould and set aside.
2. Bloom gelatine powder with water and set aside.
3. In a saucepan, bring passionfruit pulp and warm water to boil. Remove from heat and let cool for 5 mins.
4. Stir in the bloomed gelatine and stir with a whisk until fully melted.
5. Pour the jelly mixture to the silicone mould carefully.
6. Put in freezer for 2-3 hours until completely set before unmoulding.

Pistachio Bavarois

1. Bloom gelatine powder with water and set aside.
2. In a saucepan, bring milk and cream to boil.
3. While the milk and cream are heating up, whisk together egg yolk and sugar in a mixing bowl.
4. As soon as the milk and cream are boiling, slowly pour them over the egg-sugar mixture while whisking it continuously.
5. Pour the whole mixture to the saucepan and cook it like an anglaise on low heat while continuously stirring with a spatula (remember to scrap the bottom of the pan to prevent any sticking & burning).
6. Once the mixture reaches 85C, remove from heat and strain it to another bowl to prevent further cooking.
7. Stir in pistachio paste and vanilla with a whisk until fully incorporated.
8. While the mixture is still hot, stir in the bloomed gelatine and mix until fully melted. Let cool.
9. While the mixture is cooling, semi-whip the cream.
10. Gently fold in the semi-whipped cream when the mixture is cooled to 40C.

Milk Chocolate Coating

1. Using a double boiler or microwave, melt the milk chocolate. (If you’re using a microwave, please check every 15 secs and stir to avoid burning the chocolate)
2. Whisk in vegetable oil until fully emulsified. You can use a stick blender for better emulsion.
3. Add the chopped pistachio and mix.
4. Transfer it to a rather narrow container that is deep enough to dip the bavarois in later on. Cover with cling wrap and set aside in room temperature until ready to use.

Assembly

Note: Mind that because I used a cube silicone mould, I could do it in the normal order instead of the upside down way because it wouldn’t affect the result. However, if you desire to use a different silicone mould, you may have to do it the upside down way. 

1. Put the sponge circle in the centre of the silicone mould. 
2. Then, put the passionfruit jelly on top of the sponge. Carefully pour in the pistachio bavarois into the mould until full. Remove any excess mousse with a small palette knife. Keep in the freezer for 6-8 hours or preferably overnight before unmoulding. 
3. After all bavarois is unmoulded, place two toothpicks at either end of the bavarois and dip it in the milk chocolate coating until evenly coated. Gently place the bavarois to a cooling rack to allow the excess coating to drip off. Remove the toothpicks very carefully by twisting them. Store in fridge for 10-15 mins until the chocolate coating is set. Before serving, garnish with gold lustre powder.