Preheat the oven to gas 4 / 180C / 350°F and grease & line 2 x 8" round cake tins
Mix half of the milk with the vinegar and set aside
Put the rest of the milk in a saucepan with the lavender. Boil it then take it off the heat and let it stand for 5 minutes to infuse the flavour before straining
Put the sugar, oil, vanilla, vinegar milk and the lavender milk into a bowl and mix together
In another bowl mix together the flour, starch, baking powder, bicarb and salt
Stir the wet ingredients into the dry until just combined then split between the 2 tins and put straight into the oven
Bake for 30 minutes or until a toothpick tests done
Turn out onto a wire rack to cool
Meanwhile make the lavender syrup by bringing all the syrup ingredients to the boil in a saucepan. Let simmer, stirring occasionally until thickened. Take off the heat, strain and let cool
To make the raspberry sauce, boil the berries, sugar and water until the berries are soft and falling apart
Stir in the cornstarch mixture, boil to thicken then strain and let cool
For the buttercream, mix the butter & icing sugar together until light and fluffy. Add the vanilla, zest and lemon juice, adding more juice or some rice milk to achieve a good spreading consistency
When everything has cooled, set one of the cake layers onto a plate or cake board and use a cocktail stick to pierce the cake surface randomly
Brush the whole of the top surface and sides with half of the lavender syrup then add a layer of lemon buttercream
Put the 2nd cake layer on top, again pierce then brush a coating of lavender syrup on top and sides, then spread the rest of the buttercream over the top and sides of the assembled cake
To serve, pour some of the raspberry sauce on a plate and sit a slice of cake on top
