Grease two (160ml capacity) moulds or ramekins. Place the milk in a microwave-safe jug. Heat in microwave on HIGH for 20 seconds or until hot.
Sprinkle gelatine over 2 tablespoons boiling water in a small heatproof jug. Stir with a fork until gelatine has dissolved. Stir gelatine and sugar into hot milk until sugar dissolves.
Add cream to milk mixture; mix well. Divide the liquid among prepared moulds and cover with cling film. Refrigerate for 6 hours or until set.
Lightly grease a large non-stick frying pan with oil and heat over medium heat. Cook peaches, cut side down, for 2 minutes, then turn.
Combine brown sugar, juice and 2 tablespoons water in a small bowl; pour liquid over peaches and bring to the boil. Simmer for 1 minute or until sauce thickens slightly. Remove from heat and set aside to cool.
Dip each panna cotta mould briefly in a bowl of hot water and turn the panna cottas out onto serving plates. Serve with peaches and drizzle with syrup.