UserControl as DataTemplate inside ListBox

I want to reuse my UserControls in other UserControls like page or window as DataTemplates, in this example inside a ListBox. Everything is MVVM.

I've a UserControl called "CardControl" to display a simple object "Card". Card has two Properties, "ID" and "CardImage". The controls DataContext is set via XAML. If I open this UserControl in VS or Blend it shows me the dummy Card that I have defined in the corresponding ViewModel.

Now I have another UserControl called "CardSetControl", which should display a collection of Cards. So the ViewModel has one property of type ObservableCollection<Card> called "Cards".

Here is the code:

<ListBox x:Name="MyList" ItemsSource="{Binding CardSet.Cards}">
  <ListBox.ItemTemplate>
    <DataTemplate>
      <StackPanel>

        <!-- WORKING, but not what i want -->
        <TextBlock Text="{Binding ID}" /> // would display ID of Card
        <Image Source="{Binding Image}" /> // would display Image of Card

        <!-- NOT WORKING, but this is how i want it to work -->
        <UserControls:CardControl DataContext="{Binding "Current listbox item as DataContext of CardControl???"}" />

      </StackPanel>
    </DataTemplate>
  </ListBox.ItemTemplate>
</ListBox>

After reading tons of articles about MVVM and DataContext/Binding I still didn't get it to work. How is this whole hierarchical USerControls/DataContexts thing done the best clean way?