Preheat oven to 350F.  Over a bain-marie, melt the butter. Add sugar and whisk. Add chopped chocolate. Whisk for two minutes. Add eggs one at a time, whisking after each addition. Sift together cocoa powder and cornstarch. Add salt and mix. Transfer to prepared brownie pan. Bake for 23 minutes. Cool in pan to room temperature. Cut into 1x1” cubes

Combine all in a pan and saute until softened, allow to cool fully.  

Line a high-sided pan with with oil and parchment paper so that the parchment paper is 2” above the height of the top of the vessel.  Set aside.

In a high sided pot and using a candy thermometer, combine sugar, corn syrup, water and vanilla.  Bring to 300 F making sure to use a candy thermometer. Remove from heat and add baking soda and whisk until soda puffs and is incorporated, be very carfeful.   

Immediately transfer to greased lined dish and cool completely, do not touch hot sugar or tray. Once fully cool, break into pieces and set aside for garnish.
 

In a medium sized bowl whisk together yolks, sugar and salt until the mixture is well combined and smooth.  

In a saucepot, combine 1C of heavy cream and ground espresso, scold the cream and allow the coffee to steep for a two minutes.  Strain through a fine chinoise or a cheese cloth making sure to squeeze out all the moisture.  

Slowly and in 3 equal batches, transfer the hot cream into the yolk mixture while whisking.  Once evenly combined, place bowl over a double boiler and cook to anglaise stage.  Transfer to a clean vessel and cover with plastic touching the surface.  Allow to cool fully then transfer to fridge to cool.  

Beat 1 C of heavy cream to soft peaks.  Fold heavy cream into chilled anglaise mixture.  Chill.

Beat remaining 1/2 C of heavy cream with icing sugar to soft peaks for garnish.