Pre-heat the oven to 175°C / 350℉.
Grease (or line) a small springform pan (mine is 18cm / 7").
In a pan, melt the butter and chocolate together.
Add the coffee (or milk). Stir to combine.
In a bowl, beat the eggs and then whisk in the sugars.
Stir in the cocoa and flour.
Bake for around 18-25 minutes (depending on how molten you want your centre) - see note 2.