Microsoft has added Microsoft To-Do integration to Cortana in Windows 10.
This means that you can add items to your To Do list using Cortana, and view your Cortana To Do list in Microsoft To-Do.
The new version of Cortana is available on Windows 10 Insider Preview Build 18267+ in English speaking countries (Australia, India, US, or UK region) and requires Cortana to be connected to your Outlook or Office 365 account at Cortana > Notebook > Manage Skills > Connected services.
Microsoft says their To Do and Notes apps are all about expanding your memory. You can read more about the integration at Microsoft here.