Wild garlic flower and cream cheese tart

This is a recipe to make when you have left-over egg whites. I have based it on a sweet medieval recipe for sambocade, which was made with elderflowers. Here the tart is savoury using wild garlic flowers. Egg whites alone keep the tart filling elegantly pale. It would be a perfect vegetarian first course for a spring lunch when wild garlic flowers are in bloom. To prepare the flowers, separate the flower heads and chop the stems as you would for chives; both parts are used.