Pre-heat the oven to 450 degrees Fahrenheit.
In a double boiler, over simmering water, melt the butter with the dark chocolate. In a medium bowl, beat the eggs with the egg yolks, sugar and salt at high speed until thickened and pale.
Sift the flour into this mixture and gently stir to combine into a batter.
Transfer the batter to a resealable plastic bag. Snip one corner of the bag with scissors to create an opening.
Arrange the ramekins in a casserole dish.
Generously coat the inside of the ramekins with melted butter and pipe the batter into them.
Bake in the preheated oven for 8-9 minutes.
Remove from the oven and let them sit for 2-5 minutes to allow them to cool slightly.
Loosen the edges from the ramekin with a knife. Invert each cake onto a plate and dust with powdered sugar. Enjoy with a scoop of vanilla ice cream.
