Put the lemon zest and juice, sugar and eggs into a large bowl and whisk until smooth, then stir in the cream. Pour the lemon cream into the 6 ramekins and put the ramekins in a deep roasting dish. Make a bain-marie by half filling the dish with hot water.
When cold, dust with icing sugar and place under a hot grill until the icing sugar caramelizes and turns golden. Cool again before serving.