Peach and Basil Gelato
Make the peach puree: In a large saucepan, add the peach slices, sugar and water. Bring to a boil, then simmer for 20 minutes or until peaches are very tender. Stir in the lemon juice and basil leaves. Puree to a fine consistency using a stand or immersion blender. Transfer to an airtight container and refrigerate until the puree is cool, at least 2 hours. The puree can be prepared up to a day in advance.
Make the gelato: Pour whipping cream, vanilla extract and 310 mL (1 1/4 cups) of the milk into a saucepan. Warm over medium heat until just bubbling around the edges (no need to bring it to a boil).
Meanwhile, in a small bowl, whisk together the remaining milk (250 mL/1 cup), the sugar and the cornstarch. Remove the saucepan with the hot milk and cream mixture from the heat and whisk in the cornstarch mixture. Return the saucepan to medium heat and cook, stirring regularly, until the sugar is dissolved and the mixture thickens slightly, about 6 to 8 minutes.
Place the egg yolk in a medium-sized bowl and whisk until it is pale and slightly thickened, about 30 seconds. Slowly pour one ladleful of the hot milk mixture into the yolk, whisking constantly, then slowly pour the egg yolk mixture back into the saucepan, whisking to combine. Stir in the peach liqueur, if using. Remove from heat. Let cool to room temperature, then transfer to an airtight container and refrigerate until the custard is cool, a few hours to overnight.
Whisk the peach puree into the custard, then strain the custard for a silky consistency. Pour into the bowl of an ice cream maker and freeze per the manufacturer’s instructions. Transfer the gelato to an airtight container and freeze until firm, about two hours.
Always take the gelato out to warm at room temperature 10 to 15 minutes before serving to make it easier to scoop and achieve the perfect texture.