Preheat the oven to 180℃ or 350℉. Grease an ovenproof dish and put it aside.
In a larger bowl, using a hand mixer, whisk together 6 egg yolks, 4 whole eggs, ¾ cup sugar, a pinch of Celtic salt, and vanilla.
In a separate large bowl, combine 180g (6.35 oz) vanilla custard powder and 35g (1.23 oz) of cornstarch. Stir until homogenously combined.
In a large jug, mix the milk and cream together, and stir until combined.
Gradually whisk a little of the milk into the dry ingredients to form a smooth paste with no lumps. Slowly pour the remaining milk into the egg mixture while whisking continuously. Then add the custard mixture to the egg-and-milk mixture and blend until completely smooth.
Cooking the Flan
Stage 1 - Stove
Pour the custard mixture into a saucepan over medium heat. Whisk continuously until it begins to bubble and thicken. Reduce the heat to low and continue whisking until thick enough to leave visible whisk trails. Remove from the heat.
Stage 2 - in the oven
Transfer the custard into the greased ovenproof dish, if using any prunes, scatter them evenly over the custard.
Bake for about 80 minutes or until set with a deep golden-brown top.
Serving it
Remove from the oven and allow it to cool.
Once completely cooled, you can place it in the fridge for an hour or longer to make it ready to be served.
Notes
Without the cream, the texture would be noticeably less rich and less silky. The cream contributes fat, smoothness, and helps the baked flan get a softer interior.
Please note that the prunes are not included in the nutritional facts in this recipe!
The vast majority of the time, I add the dried prunes as I really love this addition - it is the way I have had this beautiful flan in France, and I love it. This time, in this recipe, I did not add the prunes, as I did not have any, but if you do and would like to try it that way, simply add the prunes on top (scattered around or arranged in a circular way) just before transferring the flan to the oven.