JSON Models with Children

I'm still learning .NET (and .NET Core), and am having problems wrapping my brain around something. So I'm hoping someone can give me a nudge...

I'm trying to return some JSON data from a Controller (it's some info from an LDAP query) so I can populate a JQuery tree item on the client side. I can get top-level objects to populate just fine within my tree with my Controller returning something like this (the values are just hardcoded to show what I'm doing):

List<TreeViewItem> treeData = new List<TreeViewItem>()
{
   new TreeViewItem() { Title = "MyFirstObject", Folder = true, Children = false },
   new TreeViewItem() { Title = "SomeOtherItem", Folder = true, Children = false },
   new TreeViewItem() { Title = "AnotherRandom", Folder = true, Children = false },
};

return Json(treeData);

But I'm running into issues with children objects for the tree. Here is a hardcoded sample of what format the tree plug-in (FancyTree for JQuery) wants:

{title: "MyFirstObject", folder: true,},
{title: "SomeOtherItem", folder: true, children: [
   {title: "subItem1", folder: true},
   {title: "subItem2", folder: true},
   {title: "subItem3", folder: true}
]},
{title: "AnotherRandom", folder: true,}

How can I include the information for children, while still using a Model-based methodology to store my data?

Thanks!

(and thanks to everyone that have replied to any of my other posts - it's been extremely helpful in getting up to speed with .NET!)