1 For the cupcakes: heat the oven to 180°C (160° fan) 350°F gas 4. Place paper cases in a 12 hole bun tin.
2 Put the xylitol and flour into a food processor, add the lavender flowers and process to grind the flowers. Sift the mixture into a mixing bowl, discarding any pieces of flower left in the sieve.
3 Beat in the butter, eggs and milk until well blended.
4 Spoon the mixture into the paper cases and bake for about 20 minutes, until golden and springy to the touch. Remove from the tin and place on a wire rack to cool.
5 For the buttercream: heat the milk and lavender in a small pan over a low heat and bring to a boil. Immediately remove the pan from the heat, cover and set aside for 30 minutes to infuse and cool.
6 Beat the butter until soft and creamy. Sift in the powdered xylitol and beat well.
7 Pour the lavender milk through a sieve into the mixture. Add the vanilla and lilac colouring and beat well until smooth.
8 Spoon into a piping bag and pipe on top of the cakes.
9 For the lemon marshmallow: heat the milk and xylitol in a small pan over a very low heat until the sugar has dissolved.
10 Melt the marshmallows in a heatproof bowl over a pan of simmering (not boiling) water. When they start to soften, add the boiling water and stir.
11 Remove from the heat and beat in the lemon juice, food colouring and milk/xylitol mixture until cooled.
12 Quickly spoon into a piping bag and pipe on top of the cakes. Decorate with dried lavender.