Peel the peaches.
Cut them into small pieces and blend them with the mixer until you get a puree with a few drops of lemon to prevent the puree from becoming dark.
In a bain-marie, whisk the egg yolks with sugar with the electric whisk for a few minutes.
Pour the peach puree flush and continue whipping for another minute (the long whipping will allow you to incorporate a lot of air, essential for the success of a semifreddo).
Let it cool down.
Whip the cream until stiff and gently add it to the yolks and peach puree mixture.
Distribute the mixture in the mold you prefer and let it cool in the freezer for at least 6 hours.
Remove your semifreddo from the freezer just before serving(melt quickly enough), soaking the mold for a few seconds in hot water, and turn it upside down on the plate.
Decorate with peach slices and mint leaves.