Method

• 1.
  To make the crunchy buckwheat, cook buckwheat groats according to packet instructions until tender. Drain and spread out on a tray lined with a clean tea towel. Chill overnight, uncovered, to dry out.
• 2.
  Half-fill a deep-fryer or large saucepan with vegetable oil and heat to 200°C (a cube of bread will turn golden in 35 seconds when the oil is hot enough). In 2 batches, deep-fry cooked buckwheat for 30 seconds-1 minute until lightly golden and crunchy. Remove using a slotted spoon, drain on paper towel and set aside to cool completely.
• 3.
  Preheat oven to 180°C. Grease a 20cm x 30cm lamington pan and line the base and sides with baking paper. Place butter and chocolate in a heatproof bowl set over a saucepan of gently simmering water (don’t let the bowl touch the water). Stir mixture occasionally until melted and smooth. Remove bowl from heat and set aside to cool to room temperature. If chocolate mixture starts to set, gently heat over simmering water until melted again.
• 4.
  Sift the flour, cocoa and a pinch of sea salt flakes into a bowl and set aside. Place the eggs, sugar and vanilla in the bowl of a stand mixer fitted with the whisk attachment and whisk for 8-10 minutes until pale and fluffy.
• 5.
  Working in 3 batches, gently fold the chocolate mixture into the egg mixture until just combined, making sure you scrape the bottom of the bowl to incorporate all the ingredients.
• 6.
  Sift half the flour mixture over the chocolate mixture and gently fold through. Repeat with the remaining flour mixture, mixing until just combined (the mixture should be quite runny). Gently fold in the crispy buckwheat, then pour the mixture into the prepared baking pan and spread evenly.
• 7.
  Bake for 40 minutes, rotating pan halfway through cooking time, until the surface is smooth and shiny with one or two cracks appearing. Cool brownie in the pan, then cut into 24 squares to serve. Store in an airtight container for up to 5 days.