Preheat oven to 350˚F. Butter the inside of a 9” springform pan.
Place the butter and chocolate in the top of a double boiler and melt with a spatula until smooth (I used a salad bowl on top of a small boiling pot of water). It will start off very clumpy, but work through until it’s nice and smooth. If boiling water gets too aggressive lower it to medium or even low. When ready remove from head and set aside.
Place egg whites and salt in a medium bowl. Place the yolks and sugar in a slightly larger bowl and set aside. Using a handheld mixer, beat egg whites on medium speed until stiff peaks form, about 2 minutes (I did it manually since hubby was sleeping and didn’t want to make too much noise if you want a 10 min vigorous arm workout, you should try it, but I’m warning you it was painful and there will be sweat).
Transfer the beaten egg whites to the yolk and sugar bowl and beat on medium speed (or by hand as I did) until light in colour and batter makes ribbons when you lift the whisk, about 2 minutes.
Using a spatula, stir in the chocolate mixture and then fold in the flour (a few tbsp at a time) and the extracts until well blended.
Pour the mixture into the buttered pan and bake for about 35-40 minutes or until puffed and shiny and cake is beginning to crack on top.
Cool on a wire rack. When ready to serve, run a thin knife around the edge of the pan to release the cake. Remove the outside ring and dust the top with lots powdered sugar and enjoy!