4: ...then turn them out onto a sheet of baking paper on a baking sheet.
5: Brush with more oil, then season with salt and pepper.
6: Bake until nicely colored. Meanwhile, reheat 300 g cancoillotte over low heat.
7: Serve the potatoes, well grilled and generously topped with hot cancoillotte.
Remarks
If you don't have cancoillotte, replace it with a mixture of 1/3 cream, 2/3 the cheese of your choice, grated or cut into tiny pieces. In another version, you could deep-fry the mashed potatoes.