Combine the pistachio paste and glucose syrup and mix well.

Add the egg whites, gradually, mixing all the time at medium to high speed.

Mix the powdered sugar and almond flour then add it to the pistachio and whites mix. Continue whipping at high speed.

Stream in the vegetable oil, then do the same with the heavy cream.

Mix the flour with the salt and baking powder and add it to the batter.

Combine well then transfer into a 35x25cm cake frame.

Level the batter well then bake in the preheated oven at 180C for 20-25 minutes or until slightly golden brown. Don't overbake as it might dry out!

Combine the eggs, sugar, lemon and lime juice plus zest in a small pot and place over low heat.

Cook, mixing all the time, until the mixture begins to thicken.

Strain through a fine sieve then cool down to 40C.

Add the softened butter and blend well.

Keep in the fridge until assembling.

Combine the butter and pistachio paste and mix well.

Add the sugar and salt and give it a good mix.

Keep aside until assembling.

Combine all the ingredients in a pot and bring to a boil.

Strain through a fine sieve and cool down.

Combine all the ingredients in a bowl and mix well.

Spoon 1/4 of the croustillant into small pieces on a sheet of baking paper and refrigerate. These will be the decor later.

Keep the remaining croustillant in the bowl at room temperature until assembling.

Cut 2 discs of pistachio sponge cake - 18cm diameter. Keep the cake scraps to build a third layer of sponge cake later.

Arrange a sheet of acetate in a 18cm diameter cake ring.

Using the cake scraps, build your first layer, pressing the cake well to ensure and even layer.

Brush the sponge cake with sugar syrup then spoon in 1/3 of the buttercream and level well.

Add 1/3 of the citrus cremeux, followed by pieces of croustillant.

Place a disc of sponge cake on top and press to make sure the cake is leveled.

Follow the same layering as before: syrup, 1/3 of the buttercream, 1/3 of the citrus cremeux, croustillant.

Place the last disc of cake on top and press well.

Cover the final layer of cake with the remaining pistachio buttercream and refrigerate at least 6 hours.

Keep the remaining 1/3 of citrus cremeux for decorating later.

Once the cake has chilled, remove the cake ring and acetate sheet.

Decorate with the citrus cremeux you kept aside and the croustillant pieces. The final touch might as well be a few slices of lemon or lime.

Enjoy!