Preheat the oven to 180C/350F/Gas 4. Grease 12 dariole moulds and line the bottoms with a circle of greaseproof paper.
Heat the dates, 450ml/16fl oz water and bicarbonate of soda in a saucepan over a low heat until simmering, stirring continually. Simmer for 20 minutes, or until the dates break down into a paste. Remove the date mixture from the heat and set aside to cool slightly.
Meanwhile, cream the butter and sugar together in a bowl until light and fluffy. Add the eggs, cooled dates, cocoa powder, flour and mix until well combined.
Divide the batter between the moulds, place them into a large baking tray and bake in the oven for 25-30 minutes, or until well-risen and springy to the touch. Remove form the oven and set aside to cool.
Meanwhile, for the sauce, heat the butter, sugar and cream together over a high heat for five minutes, or until smooth and well combined.
Stir in the grated chocolate until melted and remove from the heat.
To serve, turn the puddings out onto a serving plate, spoon over the sauce and serve with clotted cream.