Place the measurement water, sugar and vanilla extract in a saucepan, cook over a low heat until the sugar dissolves, then cook over a high heat for 5–10 minutes until syrupy.
Add the peach halves and cook for a further 5 minutes until tender, then leave to cool. Remove the skins and thinly slice the peaches.
Arrange the peach slices, ice cream and half the raspberries in sundae glasses. Press the remaining raspberries through a sieve to make a coulis, drizzle over the top of the sundaes and serve with biscuit curls.