What is the "Rails-way" or the "Ruby-way" of doing the following:

In my controller, I'm creating and instance of an Options class. It will be initialized with information in the params hash if the params hash exists. Otherwise, it will check the sessions hash for the information. Finally, it will initialize with defaults if neither params nor session has the data it needs. Here is how I'm doing it now (it works fine, but it seems a little ugly):

if params[:cust_options]
  @options = CustomOptions.new( params[:cust_options] )
else
  if session[:cust_options
    @options = CustomOptions.new( session[:cust_options] )
  else
    @options = CustomOptions.new
  end
end

session[:cust_options] = @options.to_hash

Like I said, everything is working fine, I'm just looking for a more idiomatically Ruby way of writing this block of code.