Making the Pastry Cream

Cup of Yum
1. Place the milk and salt in a medium-sized saucepan and bring to a simmer gently on low heat.
2. In a separate bowl, whisk together the egg yolks and caster sugar. Add the cornstarch along with the flour and whisk until combined.
3. Pour about half of the simmering milk over the sugar and egg mixture, whisk well, then transfer it all back onto the saucepan.
4. Keep whisking until it boils, add the butter and vanilla extract, then whisk for another minute before removing from the heat. 
5. In a small bowl, stir the gelatine powder and a little bit of cold water to dissolve it. 
6. Add it to the pastry creme and whisk well until dissolved and combined. 
7. Transfer the pastry cream to a clean bowl or tray, cover with cling film touching the surface, and place in the fridge to chill for a couple of hours.

Making the Choux Pastries

1. Start preparing choux pastries while the pastry cream is cooling down.
2. Preheat the oven to 200° C (390° F) fan oven.
3. Melt the butter in a medium-sized saucepan over medium heat and add water.
4. Bring it to a boil, lower the heat then add the flour, salt, and sugar all at once.
5. Stir vigorously with a wooden spoon until the flour is completely incorporated and a thick dough turned into a ball.
6. Gently cook the dough ball for 1 minute, stirring with a wooden spoon.
7. Remove from heat and let it cool down for 10 minutes before adding the eggs.
8. When the dough has cooled down, add the eggs bit by bit, mixing well after each time until the eggs are totally incorporated. You can do that stage with a stand mixer fitted with a paddle attachment or a hand mixer.
9. Stop adding the eggs when you reach the right texture which is shiny, thick, and smooth with a pipeable consistency. You might end up with some left eggs which you can use to eggwash the pastries.
10. Transfer the dough into a piping bag with a large round nozzle attachment.
11. Line 2 baking trays with parchment paper. Using a pen, draw a circle size of 25cm (10") Ø on each tray.
12. Pipe one 23 cm (9") Ø circle and two 5 cm (2") mounds on each tray. You should have 2 flat large and 4 small choux pastries in total.
13. Cook for 20 mins in a 200° C (390° F) preheated fan oven until golden brown then reduce the heat to 150° C (300° F).
14. Cook for another 10 minutes then remove the small balls from the oven. Continue cooking the larger circles for another 15 minutes.
15. Remove the trays from the oven and let the pastries cool down while preparing the diplomat cream.

Making the Diplomat Cream

1. Once the pastry cream has cooled down, start whipping the cold double cream or whipping cream until you reach stiff peaks.
2. Whisk the pastry cream to loosen it in a large bowl, then gently fold the whipped cream in 3 or 4 times. Transfer into a piping bag with a large round nozzle.

Preparing the Chocolate Ganache

1. Chop the chocolate into small pieces using a serrated knife and place in a medium heat-proof bowl.
2. Heat the cream in a small saucepan over medium heat until it begins to gently simmer making sure it's not rapidly boiling.
3. Pour over the chocolate, then let it sit for 2-3 minutes to gently soften the chocolate.
4. Stir until completely combined and the chocolate has melted with a metal spoon or rubber spatula. The finer the chocolate, the quicker it will melt with the cream.
5. Start assembling the cake before the chocolate starts to set.

Assembling the Chocolate Eclair Cake

1. Line your 25 cm (10") Ø springform cake tins side with silicon paper. (It will make it much easier to remove the cake from the tin).
2. Place one layer of large choux pastry into the cake tin, pipe ½ of the diplomat cream on top spread it, and even out the surface with a spatula or a butter knife. 
3. Place the bananas and strawberries on top of the diplomat cream.
4. Split open the 4 small choux pastries, dip them in the chocolate ganache then place them on top of the fruits.
5. Continue this step until you create a layer of chocolate-dipped choux pastries.
6. On top of the small choux pastries, pour in ⅔ of the chocolate ganache.
7. Pipe the other ½ of the diplomat cream on top spread it and even out the surface with a spatula or a butter knife.
8. Place the second large choux pastry on top of the diplomat cream and pour the rest ⅓ of the chocolate ganache on top.
9. Refrigerate overnight until it sets then remove the ring carefully before serving.