Cheesy Scalloped Potato and Leek Casserole
This cheesy scalloped potato and leek casserole turns simple potatoes, sweet leeks, cream, and nutty Gruyère into a rich, golden dinner side that tastes special without feeling fussy.
It is the kind of dish that makes the kitchen smell like butter, garlic, thyme, and bubbling cheese. The potatoes bake until tender, the leeks melt into the cream, and the top turns crisp and deeply golden.
Why You’ll Love This Recipe
- Rich and creamy: The cream, milk, Gruyère, and parmesan bake into a silky sauce that coats every slice.
- Sweet, savory flavor: Leeks add gentle sweetness while garlic and thyme keep the casserole warm and aromatic.
- Simple ingredients: Potatoes, leeks, dairy, cheese, and pantry seasonings do all the work.
- Great for sharing: It serves 4 as a generous side and pairs well with roast chicken, baked fish, ham, or a green salad.
Fabian’s Budget Tip: Gruyère gives the best nutty flavor, but you can stretch the budget by using half Gruyère and half sharp white cheddar. Buy a small wedge of parmesan and grate it yourself, since it usually tastes better and lasts longer than pre-grated cheese.
Ingredients (Serves 4)
- 2 pounds Yukon Gold potatoes, thinly sliced (900 g)
- 2 medium leeks, white and light green parts only, sliced and well rinsed (about 250 g)
- 2 tablespoons unsalted butter (28 g)
- 2 garlic cloves, minced (about 6 g)
- 1 teaspoon fresh thyme leaves (1 g), or 1/2 teaspoon dried thyme
- 1 cup heavy cream (240 ml)
- 1 cup whole milk (240 ml)
- 1 teaspoon fine salt (6 g)
- 1/2 teaspoon black pepper (1 g)
- 1 cup shredded Gruyère cheese (100 g)
- 1/2 cup finely grated parmesan cheese (45 g)
- Extra butter for greasing the baking dish (about 5 g)
Step-by-Step Instructions
1. Heat the Oven and Prepare the Dish
Heat the oven to 375°F (190°C). Rub a small baking dish with butter, using enough to coat the bottom and sides. A dish around 8 by 8 inches works well for 4 servings.
2. Slice and Rinse the Leeks
Trim the dark green tops and root ends from the leeks. Slice the white and light green parts into thin half circles. Rinse them well in a bowl of cool water, then lift them out with your hands so the grit stays behind. Pat them dry with a clean towel.
3. Sauté the Leeks
Melt the butter in a skillet over medium heat. Add the leeks and cook for 6 to 8 minutes, stirring often, until they soften and smell sweet. Add the garlic and thyme, then cook for 1 minute more. The garlic should smell fragrant, not browned.
4. Season the Cream Mixture
In a bowl, stir together the heavy cream, milk, salt, and black pepper. Add half of the Gruyère and half of the parmesan. The mixture should look creamy and speckled with cheese.
5. Layer the Potatoes and Leeks
Arrange one third of the sliced potatoes in the baking dish, slightly overlapping them. Scatter one third of the sautéed leeks over the potatoes. Pour over a small amount of the cream mixture. Repeat the layers two more times, ending with cream over the top.
6. Cover and Bake Until Tender
Cover the dish tightly with foil and bake for 45 to 55 minutes. The sauce should bubble around the edges, and a knife should slide through the potatoes with only gentle resistance.
7. Add Cheese and Brown the Top
Remove the foil. Sprinkle the remaining Gruyère and parmesan over the top. Bake uncovered for 15 to 20 minutes, until the top is golden, the edges are bubbling, and the cheese smells toasted and nutty.
8. Rest Before Serving
Let the casserole rest for 10 to 15 minutes before serving. This short rest helps the creamy sauce settle so the slices hold together instead of sliding apart.
Expert Troubleshooting and FAQs
Why are my potatoes still firm?
The slices may be too thick, or the dish may need more covered baking time. Slice the potatoes as thinly and evenly as you can. If the top is browning before the center is tender, cover the dish again and bake until a knife slides in easily.
Can I make this casserole ahead of time?
Yes. Bake it covered until the potatoes are almost tender, then cool it, cover it, and refrigerate it for up to 24 hours. When ready to serve, bake it covered until hot, then uncover, add the final cheese, and brown the top.
Can I use russet potatoes instead of Yukon Gold?
Yes, but the texture will be softer and a little starchier. Yukon Gold potatoes hold their shape better and taste naturally buttery, which makes them a great choice for scalloped potatoes.
How do I keep the sauce from looking watery?
Drain the rinsed leeks well before cooking them, and let the casserole rest after baking. The sauce thickens as it cools slightly. If you cut into it right away, the cream may run across the plate.
Can I make this without Gruyère?
Yes. Use sharp white cheddar, fontina, or a mix of mozzarella and parmesan. The flavor will change, but the casserole will still be creamy, cheesy, and satisfying.
Estimated Nutritional Facts
These values are rough estimates per serving and will vary based on the exact brands and amounts used.
- Calories: about 520
- Protein: about 17 g
- Carbs: about 49 g
- Fats: about 30 g
Cheesy Scalloped Potato and Leek Casserole
Ingredients
- 2 pounds Yukon Gold potatoes, thinly sliced (900 g)
- 2 medium leeks, white and light green parts only, sliced and well rinsed (about 250 g)
- 2 tablespoons unsalted butter (28 g)
- 2 garlic cloves, minced (about 6 g)
- 1 teaspoon fresh thyme leaves (1 g), or 1/2 teaspoon dried thyme
- 1 cup heavy cream (240 ml)
- 1 cup whole milk (240 ml)
- 1 teaspoon fine salt (6 g)
- 1/2 teaspoon black pepper (1 g)
- 1 cup shredded Gruyère cheese (100 g)
- 1/2 cup finely grated parmesan cheese (45 g)
- Extra butter for greasing the baking dish (about 5 g)
Instructions
- 1. Heat the Oven and Prepare the Dish. Heat the oven to 375°F (190°C). Rub a small baking dish with butter, using enough to coat the bottom and sides. A dish around 8 by 8 inches works well for 4 servings.
- 2. Slice and Rinse the Leeks. Trim the dark green tops and root ends from the leeks. Slice the white and light green parts into thin half circles. Rinse them well in a bowl of cool water, then lift them out with your hands so the grit stays behind. Pat them dry with a clean towel.
- 3. Sauté the Leeks. Melt the butter in a skillet over medium heat. Add the leeks and cook for 6 to 8 minutes, stirring often, until they soften and smell sweet. Add the garlic and thyme, then cook for 1 minute more. The garlic should smell fragrant, not browned.
- 4. Season the Cream Mixture. In a bowl, stir together the heavy cream, milk, salt, and black pepper. Add half of the Gruyère and half of the parmesan. The mixture should look creamy and speckled with cheese.
- 5. Layer the Potatoes and Leeks. Arrange one third of the sliced potatoes in the baking dish, slightly overlapping them. Scatter one third of the sautéed leeks over the potatoes. Pour over a small amount of the cream mixture. Repeat the layers two more times, ending with cream over the top.
- 6. Cover and Bake Until Tender. Cover the dish tightly with foil and bake for 45 to 55 minutes. The sauce should bubble around the edges, and a knife should slide through the potatoes with only gentle resistance.
- 7. Add Cheese and Brown the Top. Remove the foil. Sprinkle the remaining Gruyère and parmesan over the top. Bake uncovered for 15 to 20 minutes, until the top is golden, the edges are bubbling, and the cheese smells toasted and nutty.
- 8. Rest Before Serving. Let the casserole rest for 10 to 15 minutes before serving. This short rest helps the creamy sauce settle so the slices hold together instead of sliding apart.
