In a large bowl, combine the sliced peaches and granulated sugar. Gently toss to coat the peaches, then let them sit for 15-20 minutes to macerate and release their juices.

While the peaches macerate, whisk together the heavy cream, whole milk, and vanilla extract in a separate bowl until well combined.

Add the macerated peaches and lemon juice to the cream mixture. Stir everything together thoroughly.

Pour the mixture into your ice cream maker and churn according to the manufacturer's instructions, usually for 20-25 minutes, until it reaches a soft-serve consistency.

For a firmer ice cream, transfer the churned mixture to an airtight container and freeze for at least 2-4 hours before serving.