Method
 

1. Pre-heat oven to 180°C: 350°F: Gas 4.

2. In a double boiler or bowl placed over simmering water, melt the chocolate and butter, stirring, until it is smooth.

3. Remove the pan from the heat, add the egg yolks, one at a time, whisking well, and whisk in the rum .

4. Transfer mixture to a large bowl.

5. Using an electric mixer, beat the egg whites with the cream of tartar and a pinch of salt until they are at the stiff peak stage.

6. Stir a quarter of the egg whites into the chocolate mixture.

7. Then gently fold in the remaining egg whites.

8. Spoon the mixture into 6 buttered souffle dishes

9. Bake on a baking sheet in the middle of the oven for 10-12 minutes, or until they are well risen and a tester comes out nearly clean.