In a medium saucepan, combine heavy cream, whole milk, granulated sugar, salt, and vanilla extract. Heat until steaming, then whisk in egg yolks and return to heat until thickened. Strain into a large bowl.

Allow the custard base to cool slightly, then blend in apple butter until smooth. Cover and refrigerate for at least 4 hours or overnight.

Preheat oven to 375°F (190°C). In a mixing bowl, combine flour, oats, brown sugar, and cinnamon. Mix in melted butter until crumbly, spread on a baking sheet, and bake for 10-12 minutes until golden and crispy. Let cool.

Pour the chilled custard into an ice cream maker and churn according to instructions until thick.

Transfer half of the churned ice cream to a container, layer with half of the oatmeal crumble, top with remaining ice cream and crumble. Freeze for at least 4 hours.

Let the ice cream sit at room temperature for a few minutes before serving. Enjoy with salted caramel or whipped cream.