I've made it a couple of times and it's another recipe that I first got from The Spicery and I have since adapted it from the original version. If, like me, you are awful with pastry (my cases crack constantly) then just cheat and buy pre-made.
The chillies I used with this version are a mixture of Yucatan Habanero's and Ancho. The Habanero's are dried so you need to rehydrate them and be warned, these are eye-wateringly hot. You probably won't need to use a whole one!
They are quite small and fairly innocent looking at first. To hydrate them you simply rip it into small pieces, removing the stalk and the seeds, put it into a mug and cover it with boiling water. To get a very rough indication of how hot it is taste the steeping water after a few minutes.
Once you have hydrated it, remove it from the water and blend it to a puree with a splash of fresh water. Make sure your blending space is well ventilated and you may want to cover your mouth and nose with a tea towel as the fumes that come off this tiny little chilli are enough to make your eyes stream and induce a serious coughing fit. You have been warned!
The other key ingredients that are a bit less common are ground ancho chillies and ground cassia bark. You should be able to get both at good supermarkets or specialist stores, otherwise I'm sure you can get them on line. Cassia is a relation of Cinnamon so at a pinch you could always substitute although the flavor is not exactly the same. There is no real substitute for ancho chillies I'm afraid!
So here is how you make it.Heat 280ml double cream in a saucepan with 1 tablespoon ancho chilli powder, 1 teaspoon ground cassia, 1/2 teaspoon allspice, 1/2 teaspoon vanilla bean paste and as much of the habanero paste as you think people can handle (I put 1 teaspoon in). Bring to the boil then reduce and simmer for 5 minutes, stirring.
In a heatproof bowl break 200g of good quality (75% at least) dark chocolate (I used one flavoured with orange and spices for extra interest but plain, coffee or chilli would also work well, or you could combine a couple of them).
Pour the cream and spices mix over the chocolate and stir to bring it all together. When it is combined add two egg yolks and continue to stir. The texture is slightly gelatinous rather than completely liquid and it should be smooth and glossy.
Pour the chocolate filling into the sweet pastry case (about 15cm diameter ish). Cook for 15 minutes in a pre-heated oven at 150C. When the chocolate is just firm on the outside and there are no ripples it is cooked.
Scatter the top with pumpkin and sesame seeds and set in the fridge for at least one hour.
Carve into slices and serve cold either on it's own or with cream. A little goes a long way with this tart, this will feed at least 8 people! 
