1. For the honeycomb: Line a shallow baking tray with parchment paper. Place the honey, liquid glucose, water and sugar in a large heavy-based saucepan and heat gently, stirring occasionally until the sugar dissolves. Increase the heat and cook until the mixture starts to turn a light golden colour. Mix in the baking soda. The mixture will erupt into a foaming mass. Pour immediately into the prepared baking tray.
2. Leave to cool, then place in the fridge to set. This takes approx 6-10 mins. Break up with the end of a rolling pin and store in an airtight jar if not using immediately.
3. Using a blender, blitz the raspberries and blueberries together with little caster sugar until smooth. Add a drop of lavender essence. Strain the mixture through a sieve to create a fresh coulis. Taste to check consistency and flavour, add a spoonful of water or sugar as necessary.
4. Lightly mix almost all of the honeycomb through the yoghurt. Spoon into individual serving glasses and pour the coulis on top. Garnish with lavender flowers and a sprinkling of the remaining honeycomb. Serve immediately.