Encapsulating Lambda Expression / Extension Methods

Question

I have a domain model: ie. User -> Accounts -> Portfolios . Each User has a List<Account> and each Account has a List<Portfolio>. I have a user context so to access a specific portfolio, right now I do... UserContext.User.Accounts.Where().Single().Portfolios.Where().Single().Name .... I want to encapsulate all the Extension Methods with the Lambda expression .... I am thinking User.ActiveAccount.ActivePortfolio. etc but im not sure how since theres params that need to be passed.
Using vs 2k8 .net 3.5

Thanks