Azure Backup now supports selective disk backup and restore using Azure Virtual machine backup solution

Azure Backup now supports exclude-disk functionality where you get an option to backup one or a few from the many data disks in a VM. Each recovery point contains data of the disks included in the backup operation, which further allows you to have a subset of disks restored from the given recovery point during the restore operation. This provides an efficient and cost-effective solution for your backup and restore needs.
Source: Azure Roadmap