Quick Recipe Version (TL;DR)
Quick Ingredients
- 2 lb (900 g) Yukon Gold potatoes, thinly sliced
- 2 large leeks, white and light green parts only, sliced and rinsed
- 2 cans (15 oz / 425 g each) cannellini or other white beans, drained and rinsed
- 1/3 cup extra-virgin olive oil, divided
- 3 cloves garlic, finely minced
- 2 tsp fresh thyme leaves (or 1 tsp dried thyme)
- 1 tsp finely chopped fresh rosemary (or 1/2 tsp dried rosemary)
- 1 cup (240 ml) low-sodium vegetable broth
- 1/2 cup (120 ml) heavy cream or whole milk
- 1 tsp kosher salt, plus more to taste
- 1/2 tsp freshly ground black pepper
- 1/4 cup (20 g) grated Parmesan cheese, optional
- 2 tbsp chopped fresh parsley, for garnish
Do This
- 1. Preheat oven to 375°F (190°C). Grease a 9×13-inch (23×33 cm) baking dish with a little olive oil.
- 2. Thinly slice potatoes (about 1/8 inch / 3 mm) and keep in cold water, then pat dry well.
- 3. Sauté sliced leeks in 1 tbsp olive oil over medium heat until soft and sweet, about 8 minutes.
- 4. In a bowl, mix remaining olive oil, garlic, thyme, rosemary, salt, and pepper. Toss leeks and white beans with this herb oil.
- 5. Layer half the potatoes in the dish, then half the leek-bean mixture. Repeat. Whisk broth and cream together and pour evenly over layers.
- 6. Cover with foil and bake 35 minutes. Uncover, drizzle with a little olive oil, sprinkle Parmesan if using, and bake 25 minutes more until golden and tender.
- 7. Rest 10 minutes, garnish with fresh parsley and extra herbs, then serve warm.
Why You’ll Love This Recipe
- All the cozy comfort of a potato gratin, but boosted with tender leeks and protein-packed white beans.
- Olive oil, fresh herbs, and a light cream broth keep it rich-tasting but not heavy.
- Uses simple, budget-friendly pantry staples and everyday produce.
- Perfect as a vegetarian main dish or hearty side for a relaxed, rustic dinner.
Grocery List
- Produce: Yukon Gold potatoes, leeks, garlic, fresh thyme, fresh rosemary, fresh parsley.
- Dairy: Heavy cream or whole milk, Parmesan cheese (optional).
- Pantry: Extra-virgin olive oil, canned cannellini or white beans, low-sodium vegetable broth, kosher salt, black pepper, crushed red pepper flakes (optional), breadcrumbs (optional).
Full Ingredients
For the Potato, Leek, and Bean Bake
- 2 lb (900 g) Yukon Gold potatoes, scrubbed and thinly sliced (about 1/8 inch / 3 mm)
- 2 large leeks, white and light green parts only, halved lengthwise and thinly sliced
- 2 cans (15 oz / 425 g each) cannellini beans or other white beans, drained and rinsed
- 1 cup (240 ml) low-sodium vegetable broth
- 1/2 cup (120 ml) heavy cream or whole milk
- 1 tsp kosher salt, plus more to taste
- 1/2 tsp freshly ground black pepper
For the Garlicky Herb Olive Oil
- 1/4 cup (60 ml) extra-virgin olive oil
- 3 cloves garlic, finely minced or grated
- 2 tsp fresh thyme leaves, chopped (or 1 tsp dried thyme)
- 1 tsp finely chopped fresh rosemary (or 1/2 tsp dried rosemary)
- 1/4 tsp crushed red pepper flakes, optional, for gentle heat
For the Topping and Garnish
- 2 tbsp (30 ml) extra-virgin olive oil, for drizzling
- 1/4 cup (20 g) finely grated Parmesan cheese, optional but delicious
- 1/4 cup (15 g) dry breadcrumbs or panko, optional, for extra crunch
- 2 tbsp chopped fresh parsley
- Extra fresh thyme leaves or small sprigs, optional
- Flaky sea salt and extra black pepper, to finish
Step-by-Step Instructions
Step 1: Preheat the oven and prepare the dish
Preheat your oven to 375°F (190°C) with a rack in the center. Lightly grease a 9×13-inch (23×33 cm) baking dish or similar 3-quart (3 L) casserole with a little olive oil to prevent sticking. Set the dish aside.
While the oven heats, gather all your ingredients and tools: a sharp knife, cutting board, large skillet, mixing bowls, whisk, and foil for covering the dish during baking.
Step 2: Slice and soak the potatoes
Scrub the potatoes well, leaving the skins on for rustic texture and extra nutrients. Using a sharp knife or mandoline, slice the potatoes into thin rounds about 1/8 inch (3 mm) thick. Try to keep the slices as even as possible so they cook at the same rate.
Place the sliced potatoes in a large bowl of cold water as you work. This helps prevent browning and rinses off excess surface starch so the layers do not become gluey. When finished slicing, gently swish the potatoes in the water, then drain in a colander.
Spread the potato slices out on a clean kitchen towel or paper towels and pat them thoroughly dry. Removing excess moisture helps them roast and brown nicely in the oven.
Step 3: Clean and sauté the leeks
Leeks often hide grit between their layers, so cleaning them well is important. Cut off the dark green tops and root ends. Slice the white and light green parts lengthwise, then thinly slice into half-moons. Place the sliced leeks in a large bowl of cold water and separate the rings with your fingers so any dirt falls to the bottom. Lift the leeks out with your hands or a slotted spoon and drain well.
In a large skillet over medium heat, warm 1 tablespoon of the olive oil (taken from the 1/4 cup for the herb oil). Add the leeks and a pinch of salt. Sauté, stirring occasionally, until the leeks are very soft, sweet, and just starting to turn golden at the edges, about 8 to 10 minutes. If they begin to brown too quickly, reduce the heat. Remove from the heat and let cool slightly.
Step 4: Make the garlicky herb oil and season the beans
In a medium bowl, combine the remaining olive oil from the 1/4 cup, the minced garlic, thyme, rosemary, crushed red pepper flakes (if using), 1 teaspoon kosher salt, and 1/2 teaspoon black pepper. Whisk to blend into a fragrant herb oil.
Add the warm sautéed leeks and the rinsed white beans to the bowl. Gently toss until the beans and leeks are evenly coated in the herb oil, being careful not to mash the beans too much. Taste and add a pinch more salt if needed; the mixture should be well seasoned, as it will flavor the whole bake.
In a separate small bowl or measuring jug, whisk together the vegetable broth and the cream or milk. This liquid will create a light, silky sauce as it bakes.
Step 5: Build the rustic layers
Arrange half of the sliced potatoes in an even, slightly overlapping layer on the bottom of the prepared baking dish. It is fine if it looks a bit rustic and imperfect; just aim to cover the base without large gaps.
Spoon half of the leek and white bean mixture evenly over the potatoes, spreading it into a fairly even layer. Top with the remaining potato slices, again overlapping them slightly. Finish with the remaining leek and bean mixture, spreading to the edges.
Slowly pour the broth and cream mixture evenly over the entire dish, letting it seep down into the layers. Gently tap the dish on the counter once or twice to help the liquid settle.
Step 6: Bake until tender and golden
Cover the baking dish tightly with aluminum foil. Place it on the middle rack of the preheated 375°F (190°C) oven and bake for 35 minutes. This covered time allows the potatoes to steam and turn tender.
After 35 minutes, carefully remove the foil (watch for hot steam). Drizzle the top with the remaining 2 tablespoons of olive oil. If using, sprinkle the grated Parmesan and breadcrumbs evenly over the surface for a lightly crisp, gratin-style topping.
Return the uncovered dish to the oven and bake for another 25 minutes, or until the potatoes are completely tender when pierced with a knife and the top is golden and lightly crisped. If you want deeper browning, you can broil on high for 1 to 2 minutes at the end, watching very closely so it does not burn.
Step 7: Rest, garnish, and serve
Once the bake is done, remove the dish from the oven and allow it to rest on a heatproof surface for about 10 minutes. This resting time helps the layers set slightly so the portions hold together better when served, and the flavors meld beautifully.
Just before serving, scatter the chopped fresh parsley and a few extra thyme leaves or small sprigs over the top. Finish with a light sprinkle of flaky sea salt and a few grinds of black pepper to bring out the flavors.
Spoon generous portions onto warm plates or shallow bowls, making sure each serving includes potatoes, leeks, and plenty of white beans. Serve as a cozy vegetarian main course with a simple green salad or as a hearty side dish alongside roasted vegetables or your favorite protein.
Pro Tips
- Slice evenly: The thinner and more evenly you slice the potatoes, the more tender and cohesive the layers will be. A mandoline makes this fast and consistent.
- Season in layers: Taste the leek and bean mixture before layering and make sure it is well seasoned; the potatoes will soak up that flavor as they bake.
- Do not skip drying the potatoes: Excess water on the potato slices dilutes the sauce and can make the bake watery instead of silky.
- Choose the right beans: Cannellini or other creamy white beans work best; chickpeas tend to stay too firm for this soft, gratin-style texture.
- Rest before cutting: The 10-minute rest is key if you want neat slices rather than a loose scoop; it lets the starches set up slightly while still staying luscious.
Variations
- Extra-cheesy gratin: Layer 1 cup (100 g) of shredded Gruyère or sharp white cheddar between the potatoes and leek-bean mixture, and sprinkle more on top before the final bake for a richer, more classic gratin feel.
- Dairy-light version: Swap the cream for an equal amount of unsweetened oat or cashew milk and omit the Parmesan. The olive oil and herbs will still give you a rich, satisfying dish.
- Earthy mushroom twist: Sauté 8 oz (225 g) sliced cremini or button mushrooms with the leeks until browned and add them into the leek-bean mixture for deeper, savory flavor.
Storage & Make-Ahead
Let leftovers cool completely, then cover the baking dish tightly or transfer portions to airtight containers. Refrigerate for up to 4 days. Reheat individual portions in the microwave until hot, or place the whole dish in a 350°F (175°C) oven, covered, for 15 to 20 minutes, then uncovered for 5 minutes to crisp the top again. For make-ahead, you can assemble the entire bake up through Step 5, cover tightly, and refrigerate for up to 24 hours. When ready to cook, let it sit at room temperature for 20 to 30 minutes while the oven preheats, then proceed with baking as directed, adding 5 to 10 extra minutes if it is still quite chilled in the center.
Nutrition (per serving)
Approximate values for 1 of 6 servings (including cream and Parmesan, without breadcrumbs): about 380 calories; 14 g protein; 55 g carbohydrates; 13 g fat; 3.5 g saturated fat; 9 g fiber; 780 mg sodium. Actual values will vary based on specific ingredients and brands used.
