Possible variation: put a thinner slice of foie gras between 2 pieces of pastry that has been scattered with grated gruyère before baking.
Remarks
The pastry can be prepared several days in advance if it is kept tightly wrapped in stretch film in the fridge.
The number of fingers indicated is only approximate and will depend on the size you cut the pieces of pastry. So don't worry if you have a few more or less.
The sesame seeds can be replaced with others seeds of your choice (linseed, poppy seeds, etc.).