Pre-heat the oven to 160°C/140°C fan oven/Gas Mark 3.
Place the cream in a saucepan and put over a medium heat. Bring to an almost boil, and as soon as you see bubbles appear round the edge of the pan, take the pan off the heat.
Place the egg yolks and the 75g of caster sugar in a medium-large mixing bowl. Whisk until they are well combined and start to become paler in colour and a little fluffy. Pour the hot cream over the top of the whisked egg yolks and sugar, stirring with the whisk as you pour.
Sit the ramekin dishes in a deep roasting tray. Skim any bubbles from the surface of the custard. Carefully ladle the custard into the ramekins. Alternatively you can pour the custard from a jug for more control.
Pour in enough hot water into the roasting tin to come about 1.5cm up the sides of the ramekins. Place in the oven and bake for 25-30 minutes until the mixture is softly set. To check, gently tap a ramekin. If they are ready, they will wobble a bit like a jelly in the middle. Don't let them get too firm. Lift the ramekins out of the roasting tin to cool for a couple of minutes before placing in the fridge to cool completely. This can be done overnight without affecting the texture.
When you are ready to finish the crème brûlées, place the 100g caster sugar in a pan over a medium heat and gently heat until it turns a deep caramel colour. Don’t stir the sugar when it is caramelising, but you can swirl the pan to ensure even colouring. Pour or spoon a little of the caramel over each crème brûlée, and instantly scatter over some chopped pistachios. Leave for a minute or so for the caramel to set before serving.