Preheat oven to 160°C. Place the peach, cut-side up, in a roasting pan. Sprinkle evenly with the sugar. Bake for 30 mins or until the peach is very tender. Transfer to a food processor and process until smooth. Strain the mixture through a fine sieve into a small bowl.
Meanwhile, combine the cream, sour cream, milk and vanilla in a medium saucepan over medium heat. Bring to a simmer. Remove from heat. Strain through a fine sieve into a jug.
Use an electric mixer to beat the egg yolks and extra sugar in a large bowl until thick and pale. Gradually stir in the cream mixture, in batches, until combined. Pour the mixture into a clean saucepan and place over low heat. Cook, stirring, for 8-10 mins or until the custard thickens and coats the back of a spoon. Set aside to cool.
Add the peach puree and rosewater essence to the custard and stir to combine. Use a little red food colouring to tint the mixture pink. Pour into a shallow metal container. Cover with foil and place in the freezer for 4 hours or until firm.
Roughly break up the ice-cream with a metal spoon. Transfer to a food processor and process until smooth. Return the ice-cream to the metal container. Place in the freezer for 4 hours or until firm.
Tip: SERVE WITH waffle cones