For the sweet potato gratin, peel the sweet potatoes and cut them into very thin slices using a food processor. Then spread evenly in a baking dish. In a bowl, mix whipped cream and Gouda.
Season with salt and pepper, pour the mixture into the baking dish and sprinkle a pinch of dried thyme over the sweet potatoes. Bake in a preheated oven at 180° C for half an hour. Serve the sweet potato gratin.