Preheat the oven to 160℃ and line your baking tin by brushing it with olive oil and adding baking paper on the bottom, set aside.
In a large mixing bowl add the dry ingredients (flour, corn flour, cocoa, baking powder, baking soda, salt, brown sugar, castor sugar) through the sieve and sift to remove lumps. Whisk them together.
Add the buttermilk, olive oil, vanilla, eggs and whisk the mixture together until partially mixed through.
Add the hot water and whisk well until no lumps.
Pour into the prepared tin and bake for 30-40 minutes or until a tooth pick inserted into the center comes out clean. Allow it to cool completely before serving.
In another mixing bowl, beat the cream until soft peaks. Add the pistachio paste and powdered sugar, beat until combined and stiff peak form.
Once the cake has cooled down, top it with the pistachio whipped cream and drizzle over more olive oil, sprinkle of sea salt.
Slice and serve, enjoy with coffee.