1. To make the crème patissière, whisk together the egg yolks and caster sugar in a large bowl until pale, then beat in the flour and cornflour and set aside. Heat the milk and double cream in a heavy-bottomed pan until just starting to boil. Remove from the heat and leave for 30 seconds, before pouring over the eggs while whisking continuously. Once combined, transfer back to the pan.
2. Stirring constantly, slowly bring the mixture back to the boil over a medium heat. Simmer for 1 min, then remove from the heat and add the Dr. Oetker Sicilian Lemon Extract. Pour the mixture into a bowl, then lightly dust with icing sugar (to prevent a skin from forming) and leave to cool. Once cool, transfer to a piping bag with a 3mm-round nozzle, then chill for at least 1 hr.
3. For the choux pastry, bring the butter and 220ml cold water slowly to a boil in a pan over a medium heat. Once boiling, quickly add the flour and ½ tsp salt. Remove from the heat and stir continuously for 1-2 mins until the dough pulls away from the side. Transfer to a plate and leave to cool for 10 mins.
4. Heat the oven to 230C/210C fan/gas 7. Line three oven trays with baking parchment. Return the cooled dough to the pan. Add the beaten eggs a bit at a time, beating well between each addition. Beat until you have a smooth batter – it should reluctantly drop off the end of your spoon. Transfer the mixture to a piping bag with a 1cm-round nozzle. Pipe onto prepared trays into 3cm balls, leaving about 4cm between each. You should have around 36 buns in total.
5. Bake for 18-20 mins until golden and firm. Using the tip of a skewer, poke a hole into the base of each bun, sit on their sides and return to the oven for 3 mins to dry out. Remove from the oven and pipe the chilled crème patissière into each bun using the hole in the base.
6. To decorate, melt the 150g Dr. Oetker White Chocolate in a heatproof bowl set over a pan of gently simmering water. Leave until fully melted, then stir until smooth. Dip the top of each bun in the white chocolate, then top 12 with the chopped pistachios and another 12 with the Dr. Oetker Chocolatey Sprinkle Mix. Leaving the remaining 12 plain.
7. To make the wreath, arrange 14 choux buns in a circle (alternating between the plain, pistachio and sprinkle buns). Place 7 alternated buns inside the circle, then top the wreath with the remaining buns. Decorate with Dr. Oetker Wafer Daisies, Dr. Oetker Mini Wafer Flowers and mini chocolate eggs. Enjoy at its best within 2 hrs.