1. Peel the shallots, leaving them whole.
2. Put them in a saucepan with the milk, bring to a boil and cook for 10 minutes.
3. Drain them on paper towels.
4. In a frying pan, melt the butter with the sugar, add the shallots and cook over low heat for 30 minutes.
5. They should be golden and tender.
6. Arrange them in a tart dish, season with salt and pepper, and cover with the puff pastry.
7. Bake for 15 minutes at 230°C (450°F) until the pastry is well puffed and golden.
8. Unmold onto a nice plate and serve.
9. Sweet and savory lovers, you're in for a treat.