Crush the biscuits and stir in the melted butter. Press the mixture into the base of a tart dish or spring form pan.

Heat the milk and butter in a pan. Bring to the boil, then simmer for 4-5 minutes. In a separate bowl whisk the remaining ingredients together until smooth.

Pour the hot liquid over the egg mixture and mix well. Return the mixture to the pan and cook for 3-4 minutes, or until thickened. Pour the mixture into the prepared pan and allow to set in the fridge for at least 2 hours.