I wanted to do a pecan pie as well as a pumpkin pie for Thanksgiving, but it proved difficult to get corn syrup round here, and the texture of the filling just isn't right without it. I found several recipes on the internet for a chocolate filling with pecans on the top, and eventually settled on this one. I modified it a bit, mainly because I didn't want to get a whole bottle of bourbon, and we ran into the problem of the UK commercial raw pastry shells being a bit shallow again.
1 cup sugar (I used muscovado)
3 tbsp. cornflour
1/2 cup condensed milk
2 tbsp. rum
6 oz. plain chocolate, melted
4 tbsp. butter, melted
1 1/2 cup pecans
Pour into pie shell (it was just a bit too much filling, but not enough to make a second pie). Add the pecans in a circular design on top of pie. Bake for 45 minutes at Gas Mark 5.
It puffed up incredibly in the oven, and shrank considerably on cooling. I was expecting something a bit more custardy, it came out like a very rich and gooey brownie in a pastry shell, with pecans on the top. The pecans scorched a bit, you could easily have put chopped pecans in the bottom or just stirred them through the mix.
I suspect that if you let the mixture set instead of cooking it, you would have a very tolerable chocolate mousse-type thing.