Infuse the lavender in the milk for about 30mins. In a large mixing bowl, cream together the eggs yolks and sugar until pale and fluffy.
Combine the milk, chopped vanilla pod and seeds in a heavy bottomed pan, bring to the boil and simmer for 4-5mins.
Turn off the heat and allow to cool for 30 seconds. Pour the milk mixture onto the eggs and sugar, whisking continuously until smooth and creamy, then return the mixture to the saucepan.
Place the pan over a medium heat and stir continuously for 4-5mins, or until the mixture has thickened enough to coat the back of a spoon. Strain the mixture through a sieve into a bowl.
Softly whip the cream and fold into the mixture. Pour into freezer container and cover with tight-fitting lid. Place container in the freezer for 2 hours, then beat with a fork to break up the ice crystals.
Return to the freezer and repeat the process after another 2 hours. Return to the freezer until completely frozen.