Grease soup cups or ramekins with butter and dust with flour. Set aside.

 

Melt the dark chocolate in a stainless steel bowl over a pot of water on the stove (slight boil).

 

Heat the milk in a heavy bottom pot to just under a boil (stay close-it will burn easy) medium to low heat. Cool slightly and add gradually to the beaten eggs whisking gently. Gradually add the melted chocolate to the egg and milk mixture, then fold in the flour until mixed thoroughly but do not over mix.

 

Fill the soup cups or ramekins with the chocolate mixture to ¾ full.

 

Bake at 400ºF for about 10 minutes. The cake will rise above the rim and the center will remain liquid (hence the lava). 

I recommend baking the cakes just before serving. They are better hot and benefit from your favorite vanilla ice cream.