- Preheat oven to 425°F.
- Melt butter in large Dutch oven over medium heat. When the foaming subsides, add leeks and cook, stirring occasionally, until soft, about 4 minutes.
- Add garlic, thyme, salt and pepper. Cook for about 30 seconds.
- Add potatoes, broth and cream; heat to simmer. Cover, reduce heat to medium-low, and simmer until the potatoes are almost tender (a paring knife can be slipped into and out of a potato slice with some resistance), about 15 to 20 minutes.
- Transfer the mixture to a 13 x 9-inch baking dish. Sprinkle evenly with cheese. Bake until cream is bubbling around the edges and top is golden brown, about 15 minutes.
- Cool slightly before serving.
Calories 543, Carbohydrates 53g, Cholesterol 111mg, Fat 33g, Fat Calories 292, Fiber 5g, Protein 13g, Saturated Fat 20g, Sodium 709mg. Daily Values: Calcium 309.53mg 31%, Phos 277.76mg 28%, Copper 0.44mg 22%, Zinc 1.69mg 11%, Panto 1.49mg 15%, Biotin 2.68mcg 893%, Iodine 14.9mcg 10%, Magnesium 68.65mg 17%, Iron 1.62mg 9%, Vitamin B6 37%, Vitamin C 38%, Vitamin B12 8%, Vitamin D 6%, Vit E-a-Toco 4%, Vitamin A 35%. Percent Daily Values are based on a 2,000 calorie diet.