Easy Potato and Leek Gratin with Creamy Gruyère Sauce
Level up your side dish game with this creamy potato and leek gratin baked in herb-infused cream and topped with melted Gruyère. Perfect for holidays or weeknight comfort food.
Ingredients
- 2.5 lb starchy potatoes peeled and sliced 1/8 inch thick
- 1 leek thinly sliced (dark green parts removed)
- 1 yellow onion diced
- 5 garlic cloves minced
- 2 tbsp butter
- 1 bay leaf
- 2 thyme sprigs
- Pinch of nutmeg
- 1 1/2 cups Gruyère cheese shredded
- 1 cup cream
- 1/2 cup milk
- 2 tbsp Parmesan cheese grated
- 1.5 tsp salt divided
- 1/2 tsp pepper
Instructions
- In a large skillet, cook onion and leek in butter over medium-low heat until soft and lightly golden. Add half of the garlic and cook for 2 to 3 more minutes.
- In a small saucepan, heat cream, milk, remaining garlic, bay leaf, thyme, 1 tsp salt, and pepper for 5 minutes over low heat to infuse. Remove herbs and set aside.
- Toss potato slices with the leek mixture and season with 1/2 tsp salt and a pinch of nutmeg.
- Butter a small casserole dish. Layer potatoes in a slightly staggered way to create spaces for the cream to seep in. Make sure you fill the whole casserole dish so the potatoes completely fill it. (see note)
- Pour the warm cream mixture over the potatoes. Sprinkle with half of the Gruyère and cover with foil.
- Bake at 325°F for 75 to 90 minutes, or until potatoes are tender.
- Uncover, top with remaining Gruyère and grated Parmesan, and broil until golden and bubbly.
- Let rest for 10 to 15 minutes before serving.
Video
Notes
For Doubling:
- The trickiest part for me was figuring out the size of the casserole dish. I doubled this and used a 10.5" X 7.5 casserole dish and the potatoes fit perfectly but the cream was overflowing. Because of this, I reduced the total cream amount by 1/2 cup when doubling.
- A slightly larger casserole dish might work better, but you do want the potatoes to be crowded together in a staggered fashion. If you use a large casserole dish, you may need to add more potatoes to completely fill it.
