Combine butter and chocolate in a bowl and melt in a double broiler on the stove or in a microwave safe bowl in the microwave using medium heat.
Stir constantly while melting.
While the chocolate is melting put egg whites and salt in a mixing bowl (ideally to be mixed using a mixer, the old fashion way with your hand and whisk will work but you will be mixing for a while) and beat until stiff peaks form.
In a separate bowl mix egg yolks, sugar, vanilla, and slowly add in melted chocolate mixture. Fold in egg whites and pour mixture into a sprayed spring form pan.
Bake for 40 minutes or until a toothpick comes out clean (like a brownie).
Let cool a bit before removing the spring form and we recommend serving with fresh whipped cream and berries!
