Ingredients

For the filling:

3 large leeks, sliced into thin rounds or strips, soaked, rinsed, and drained *

1 bunch celery, finely sliced

2 cups dry cannellini beans or butter beans, soaked overnight then cooked **

16oz heavy whipping cream

3 tbsp extra virgin olive oil

1-2 tbsp butter (optional, depending on how rich you want it to be)

salt, freshly ground black pepper, and crushed red pepper to taste

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For the potatoes:

5 small to medium Yukon Gold potatoes, peeled and thinly sliced ***

a sprinkle of salt

a drizzle of extra virgin olive oil

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For the crispy herbed breadcrumb topping:

1 cup panko breadcrumbs

1 tsp dried basil

2 tsp dried italian seasoning

1 tbsp dried minced onions

2 tsp nutritional yeast

1/4 tsp mustard powder

1/2 tsp salt

1 tbsp extra virgin olive oil

1 tbsp butter, melted

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For layering:

1 cup shredded cheese of choice ****

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Directions

1. Prepare all your ingredients (ex: slice, rinse, and drain the leeks and thinly slice the celery). Make sure you've soaked your white beans overnight and cooked them in advance of when you're building your casserole. Or, if you need to, you can use canned beans in a pinch but that will change the texture a bit.
2. In a large saucepan, heat up the extra virgin olive oil and add in some freshly ground black pepper and crushed red pepper. Let it sizzle for 15 seconds.
3. Add in the thinly sliced celery, and some salt (maybe around 1/2 tsp). Let it cook through for about 3 minutes.
4. Stir in the leeks, and toss them to make sure they cook evenly. You'll see them wilting and turning a vibrant green. Add in some more salt (maybe around 1 tsp). Let them simmer for at least 5 minutes, uncovered, to let any excess liquid start to evaporate.
5. Stir in the white beans and optional butter, followed by the heavy cream. Let this simmer all together for another 2-3 minutes. Keep in mind this mixture will cook more once the casserole is assembled and baked.
6. In a separate bowl, toss the peeled and thinly sliced Yukon gold potatoes with a sprinkle of salt and drizzle of extra virgin olive oil. Let it sit for a few minutes, which should draw out some starch and liquid, and make the potato slices pliable and silky smooth.
7. In another bowl, mix together the melted butter and extra virgin olive oil with all the ingredients for the herbed breadcrumb topping.
8. Preheat the oven to 325°F, and grease a 8" x 12" x 3.5" casserole dish with some extra virgin olive oil.
9. Line the bottom with a layer of the potato slices. You can overlap them slightly for even coverage.
10. Add a very thin layer of cheese.
11. Spoon over 2-3 heaping ladles of the creamy leek and bean mixture, and spread it over evenly.
12. Add a very thin layer of cheese, and then repeat steps 8 through 11 until you reach the top of the casserole dish. For me, it took about 4 layers to reach the top.
13. End with a layer of the creamy leek and bean mixture, followed by a layer of cheese, then top with the herbed breadcrumb topping.
14. Cover the top of the casserole dish with aluminum foil, and bake it for 1 hour covered.
15. You can either let it rest in the warm oven for up to 1 1/2 hours (until 10 minutes before you're ready to broil it and eat). Whenever you're ready to eat, uncover the casserole dish and broil on low for 3 minutes or until the topping is perfectly golden-brown and crispy, and the edges are bubbling.
16. Take it out of the oven and let it sit for 5 minutes until cutting in and serving. My family loves serving this alongside some herbed Italian or sourdough bread!

* I like to use the entire leek, from the root to the greens and I find that it all cooks down splendidly.

** I used cannellini beans but if you want an even richer and creamier final result, you can use butter beans!

*** Try to slice them as thinly as possible, or use a mandolin slicer if you have one.

**** I just used the trusty blend of Mozzarella, Monterey Jack, and Cheddar from Trader Joe's which is a great all-purpose blend but I imagine some Gruyère would take this to the next level! This recipe is a great canvas to experiment with how different cheeses complement the potato-leek palette of flavor.