Beat the sugar, butter, salt, baking powder and espresso powder together until fluffy. Add the egg and the vanilla and scrape down the bowl. Add the flour and cocoa powder and mix until crumbly and just combined. Place onto your work surface, and shape into 2 discs. Wrap in cling film and chill for 30 mins in the fridge. Roll the dough out, dusting your table with cocoa powder, and cut 2” discs out. Place on a baking sheet and bake for 8 mins at 175C then allow to cool completely.
For the Chilli Chocolate Cream: to make the frosting beat butter and sugar together until pale and fluffy. Add in your vanilla, cocoa, chilli, salt and beat again. Slowly pour in the cream and beat again for another 3-4 mins, scraping down the bowl every now and again. Pipe a dollop of the mixture on one cookie and sandwich a second cookie on top.
For the Triple Decker Espresso Cream: whisk the cream, cocoa, sugar and espresso together until you have a soft peaks. Place a cookie down and add a dollop of the cream, stack with another biscuit and repeat until you have 4 or 5 layers. Add more cream to finish and then chocolate shavings.
For the Classic Vanilla Cream: beat the butter and shortening until light and fluffy. Add the sugar in two parts, beating in between each addition. Add the vanilla and beat again. Pipe a dollop of the mixture on one cookie and sandwich a second cookie on top.