Potato-Cauliflower Gratin

Name: Potato-Cauliflower Gratin
Yield: Makes 4–6 Servings
Cuisine: France
Ingredients: Salt and freshly ground pepper; Heavy (double) cream, 2 cups (16 fl oz/500 ml); Fresh thyme, 2 sprigs; Garlic, 3 cloves, crushed; Gruyère cheese, 2 cups (8 oz/250 g) shredded; Fresh bread crumbs, ¼ cup (½ oz/15 g) (see tip); Parmesan cheese, 1 cup (4 oz/125 g) freshly grated; Cauliflower, 1 small head, separated into florets; Yukon gold potatoes, 2 lb (1 kg), peeled and thinly sliced