1. Preheat oven to 320F (160C).
2. Scrape the vanilla bean. In a saucepan whisk heavy cream, pistachio paste, vanilla seeds and empty vanilla bean. Place the saucepan over low heat, bring to a simmer and whisk until completely smooth. Do not boil!
3. Whisk together sugar and egg yolks, add 1/3 cup of the warm cream mixture to the yolks and whisk quickly to temper the egg mixture. Add in the remaining cream, whisking constantly.
4. Strain the mixture through a fine sieve into a large bowl.
5. Pour the crème brulee mixture into 4 individual ramekins. Place the ramekins in a large roasting tray. Carefully add the boiling water into the tray until it is halfway up the sides of the ramekins.
6. Bake for 30 minutes or until set, but still a little jiggly in the middle.
7. Remove the ramekins from the hot water and let cool at room temperature. Refrigerate for at least 2-3 hours or overnight.
8. Before serving spread 1 tablespoon of sugar on top of each dish and brulee with a torch until the sugar caramelizes. Let it set for about 5 minutes before serving.