Preheat the oven to 180C/350F/Gas 4.
For the chocolate fondant, grease four dariole moulds with butter, lightly dust each with flour and place on a baking tray.
Place the dark chocolate and butter in a large bowl over a pan of simmering water (do not allow the water to touch the bottom of the bowl). Leave for about five minutes, or until the chocolate and butter have melted and then stir together. Leave to cool for a few minutes.
Carefully stir in the sugar then add the eggs one at a time, stirring well between each addition. Mix well and then gently fold in the flour.
Divide the mixture equally among the moulds. Place in the preheated oven and cook for 8-10 minutes. Remove from the oven and leave to cool for 2-3 minutes. While the fondant is in the oven, make the caramelised pears.
For the caramelised pears, heat the butter in a pan until beginning to bubble. Add the pears and fry, stirring regularly until tender (about five minutes).
Add the sugar and cook until the sugar has browned. Turn the pears in the sugar and butter until fully coated. Set aside.
For the calvados and vanilla cream, carefully fold together the cream, sugar, vanilla seeds and calvados in a bowl, making sure the sugar is well incorporated.
To serve, turn each fondant out into the centre of one of four plates - the outside should have formed a light crust around the warm and moist centre. Top with a spoonful of the calvados and vanilla cream and serve the pears on the side.