For the crème pâtissière, place the eggs, egg yolks and sugar in a large bowl and whisk until pale and smooth. Add the cornflour and whisk until incorporated and smooth.
Place the milk and vanilla paste in a large saucepan and bring just to the boil. Pour over the egg mixture slowly whisking all the time until smooth.
Place all the mixture back in the pan and bring to a simmer. Cook for three minutes, whisking all the time. Pour into a large bowl and mix in in the peanut butter until well incorporated.
Cover with cling film touching the mixture to prevent a skin forming. Set aside to cool.
For the chocolate choux pastry, preheat the oven to 190C/375F/Gas 5.
In a bowl, combine the flour and cocoa powder. Place the eggs in another bowl and whisk.
Put 110ml/4fl oz water, the milk, butter and salt in a large saucepan and bring to the boil. Remove from the heat and quickly stir in the flour mixture until well combined.
Place back on a medium heat and cook for two minutes, stirring all the time. Remove from heat and whisk in the eggs a little at a time until the mixture reaches a thick dropping consistency.
Spoon the mixture in a large piping fitted with a 15mm nozzle and set aside to cool slightly.
Cut two pieces of non-stick baking parchment to line baking trays. Mark each piece of baking parchment with six 15cm/6in long lines, spaced apart to allow for the pastry to expand as it cooks. Turn the paper over so you can see the lines through the parchment.
Dab a small spots of the choux mixture into each corner of the baking trays and stick the baking parchment to it. Pipe 12 éclairs on the lines and spray lightly with sunflower oil. Place in the centre of the oven for 25-30 minutes, or until well risen, golden-brown and crisp. You may need to swap the trays around to ensure the éclairs cook evenly.
For the strawberry jam, place the strawberries in a small food processor and blend to a purée. Transfer to a large saucepan with the lemon juice and jam sugar. Bring to the boil stirring all the time. Add a knob of butter and boil for four minutes. Pour into a heatproof bowl and set aside to cool.
For the salted peanut brittle, place the sugar in a saucepan over a medium heat and cook until it forms a caramel. Stir in the salted peanuts and pour out the mixture onto a large piece of non-stick baking parchment and allow to cool and set. (CAUTION: sugar gets very hot. Take care not to burn yourself.)
To assemble, cut the chocolate éclairs neatly in half lengthways. Pour the strawberry jam into a piping bag fitted with a 5mm round nozzle and pipe a line of jam in the base of each éclair.
Spoon the crème pâtissière into a piping bag fitted with a 15mm star nozzle and fill each éclair base over the top of the jam.
For the topping, place slices of strawberries in a row on top of the filling and put the tops on the éclairs.
Put the fondant in a large saucepan with four teaspoons of water and enough red food paste colouring to make it a deep red colour (you will only need a tiny amount). Gently heat until it reaches 38C/100F on a cook’s thermometer, stirring all the time.
Place the icing in a large piping bag fitted with a 15mm wide ribbon nozzle and pipe a line of fondant over the top of each éclair. Break the salted peanut brittle into small pieces using a rolling pin and scatter pieces on top of each éclair while the fondant is still wet.