This delicious gratin is perfect alongside roasted meats and poultry. For a twist on a classic, use both sweet and white potatoe.
Preheat oven to 400°. Lightly butter 8 x 8 shallow baking dish. In large skillet, over medium-high heat, cook bacon until crisp, set aside, drain bacon fat, reserving brown bits; reduce heat to medium and melt butter. Add leeks and garlic and continue to cook, stirring often, for about 3+ minutes, until leeks are softened. Remove from heat, season with thyme, stir in mustard and Crème Fraiche. Set aside.
Place 1/3 sliced and peeled potatoes into baking dish; sprinkle with ½ reserved bacon. Spoon ½ leek mixture over top. Repeat layer of potatoes, bacon and leek mixture. Top with remaining potatoes. Cover with foil and bake 45+ minutes or until potatoes are tender. Remove foil, sprinkle with grated Old Amsterdam and bake an additional 10 minutes or until cheese melts. Let stand 5 minutes.