Preheat oven to 180 degrees Celsius. Line an 20cm square baking pan with parchment, allowing some overhang on two sides.
Melt chocolate and butter, In a double boiler over simmering water, whisking until smooth. Or melt in a microwave using 30 second increments, stirring between increments.
Set the chocolate aside to cool to room temperature. Combine flour and salt in a small bowl
In a large bowl, whisk together eggs and sugar
Add cocoa powder, cayenne chilli paste, and crushed chilli to the egg/sugar mixture, whisking until smooth. Whisk in the cooled chocolate/butter mixture until smooth.
Fold in flour and salt and stir vigorously until batter is thick and smooth.
Spread batter into prepared baking pan.
Bake approximately 35 minutes or until a toothpick inserted into the centre comes out with just a few crumbs.
Transfer to a rack to cool completely.
When cool, use the parchment to remove from pan. Cut into squares.
