Add milk chocolate, dark chocolate, butter and coffee to a microwave safe bowl.
Microwave at 30 second intervals, stirring frequently in between, for 2-3 minutes or until fully melted. Set aside.
Whisk together eggs, egg yolks, sugar and vanilla extract until light and frothy, about 2 minutes.
Sieve all purpose flour and salt together into the egg mixture and whisk it in till all the flour is combined.
Add the egg mixture to the chocolate mixture and fold gently to combine.
Pour batter into greased and dusted ramekin moulds and fill it up until ¾th capacity (approx 100 grams per mould).
Bake at 200C for 14-16 minutes. Do not use a toothpick or skewer to check if it has baked as the centre will be gooey.
Tap the top of the mould a few times to release the cake and lift the mould carefully. Serve hot!