Add sugar to a heavy saucepan and cook over medium heat stirring continuously with a wooden spoon or heat resistant spatula. The sugar will form clumps and then turn clear as it melts. Cook until it turns an amber color.

As soon as the clumps have melted and it has turned amber, add butter, stirring constantly until it is absorbed. Add the cream, it will bubble up when added. Stir to incorporate and then let it boil for a minute without stirring. Add salt and remove from the heat and let cool.

If not using right away, warm up in the microwave so that it is spreadable.

Preheat the oven to 350º. Line a 9 x 13 inch baking pan with parchment.

Place chopped chocolate in a microwave safe bowl with butter and microwave on medium power until the chocolate has melted, stirring every 30 seconds for about 2 minutes.

In a separate bowl, whisk the flour, salt and cayenne pepper.

Whisk cocoa powder and sugar into the chocolate mixture. Add eggs and vanilla and vigorously whisk until smooth. Gently fold in flour mixture until just combined.

Bake for 30-35 minutes. Allow to cool completely before cutting.