Stephanie Alexander soft centred chocolate pudding

I usually have a bit of trouble making these (they seem to take much longer than the 12 minutes) but this time I halved recipe making just 3, and didn't weigh or measure any of the ingredients. Total success! I think the real trick is to beat eggs and sugar for the full 10 minutes. I don't think I have ever bothered to do that before.

160 g unsalted butter, softened (plus more for buttering moulds)
1/3 cup all purpose plain flour (plus more for dusting moulds)
160 g bittersweet chocolate chopped 
3 eggs
3 egg yolks
1/3 cup caster sugar

Butter 6 x 150 ml capacity moulds small bowls (I use coffee cups) very well and dust with flour. Tilt moulds so that the flour coats all the buttered surfaces, then tap firmly to remove excess flour.

Melt chocolate and 160 g butter in a double boiler or in microwave.
When melted, stir gently until quite smooth.
Remove from heat and set aside to cool a little.

Beat eggs, yolks and sugar in a stand mixer on high speed until pale and thick – about 10 minutes. 

Stop machine and sift in the flour. Set speed to low and mix.
Stop machine again and add chocolate mixture. Continue to beat on medium speed until thick and glossy, about 5 minutes.

Mix in unsifted flour, chocolate mixture and then beat for another minute. Divide batter among prepared moulds. At this stage you can refrigerate the uncooked puddings, but bring them back to room temperature before baking, and expect them to need an extra 3 minutes baking time.

Bake for about 12 minutes until puddings look set around the edges but centres move slightly when moulds are gently moved.
Remove from oven and cool slightly.
Run a flexible spatula around edges and invert puddings onto plates.