Arrange the peaches skin-side down on a baking sheet. Roast for 30 minutes.
Place the peaches, lemon zest and lemon juice, sugar and heavy cream in the pitcher of a blender. Blend until smooth. Transfer to a container and chill in the refrigerator until completely cool, about 60 minutes.
Churn in an ice cream maker, and freeze in a freezer-safe container until set.
Let sit at room temperature about 10 minutes, then scoop into bowls and enjoy.