Slice the peaches into thin wedges and layer all the fruit into a 26-cm jelly mould – it might look like a lot of fruit but you want the fruit to be dispersed throughout the jelly.
Soak the gelatine leaves in a heat-proof bowl of cold water, for 2-3 minutes. Drain and squeeze to remove excess moisture. Return the gelatine to the bowl and pour in the cordial.
Heat gently over a pan of simmering water until the cordial thickens to become syrupy, then stir in the sugar until dissolved.
Pour this into a large jug, then add the water. Stir well, then carefully pour into your mould. Don't worry if some fruit floats to the top, as it will give more detail when you turn out your jelly.
Put the jelly mould in the fridge overnight to set.
To serve, dip the jelly mould into a bowl of warm water, then loosen the sides. Carefully turn out the jelly onto a serving dish, then serve with the crème fraîche and fresh mint leaves.