Linq extension method, how to find child in collection recursive

I'm already familiar with Linq but have little understanding of extension methods I'm hoping someone can help me out.

So I have this hierarchical collection pseudo code ie:

class Product
  prop name
  prop type
  prop id
  prop List<Product> children

And I have a list of products List products.

Is there any way I can look for product in this collection by the id with a extension method ? In other words I need one item somewhere within the hierarchy.