How to create Nuget package with nested dependencies

I'm working on a .NET Core solution. For one of the projects within the solution, I need to build a Nuget package.

Project A has a reference to another project B in the solution, set up as a project reference. Project B has a dependency on a Nuget package C.

Now, when I create a Nuget package for A, it includes A.dll and B.dll but not C.dll

Can someone help me figure this out? How can I include all 3 .dlls?

Thanks,Andy