1. For the cupcakes:
Preheat the oven to 180°C (350°F).
2. Peel the apple and cut it into small cubes.
3. In a bowl, mix the eggs, milk, and oil.
4. Add the Cornstarch, rice flour, baking powder, and salt.
5. Incorporate 2/3 of the apple into this mixture.
6. Pour the batter into the cupcake molds, filling them about 2/3 full, and bake for approximately 15 to 20 minutes.
7. For the foie gras frosting:
In a blender, mix the foie gras and softened butter.
8. Season with white port, sea salt, and pepper.
9. Put the mixture into a piping bag and decorate the top of the cupcakes.
10. Use the remaining third of the apple to sprinkle small cubes on top of the foie gras frosting.