Melt the chopped chocolate and butter over a double boiler. In a large bowl whisk the eggs and sugar until pale and frothy. Quickly fold in the chocolate and flour. Divide equally into 4 buttered and floured ramekins. Bake at 350 degrees for 8-10 mins, just until sides are set and still bubbly in the middle. Let cool for a couple of minutes then invert on a plate and serve with ice cream.