This Loaded Vegetable Tart Has the Crispiest Potato Crust

In Northern Vermont, where I live, the last few days the sun has come out, the temperatures have teased a serious warmup, and the snow is finally melting. That means spring is right around the corner, which feels practically life-saving following a long, cold winter here in New England. The flavors of spring happen to be some of my favorites, and this smashed potato tart captures the bright, fresh produce of the season with melt-in-your mouth tender leeks and asparagus, complemented by nutty fontina and tangy goat cheese. The surprise element in this quiche-like tart is the golden brown smashed potato crust, which takes the place of pastry dough—it’s tender on the inside and delightfully crispy on the bottom. 

Building the Crisp Potato Crust

The challenge with making this tart was getting the potato crust just right. I tested a handful of different potatoes, pans, and even cooking methods, but the best results were borrowed from one of my favorite recipes, this top-rated Serious Eats recipe for crispy roast potatoes. No, the crust in this tart is nowhere near as crispy as the spuds in Kenji’s recipe, but I borrowed the idea of par-cooking the potatoes in water with salt and baking soda before smashing them for the crust. The alkaline water breaks down the surface of the potatoes, creating a starch slurry, which helps the potatoes brown for a darker, crispier crust.

Once the potatoes are just tender, they are added to a very well greased tart pan and smashed into an even layer. (While it's helpful to have a tart pan with a removable bottom, you can also make the tart in a pie pan, if that's all you have.) After the potatoes are smashed and formed into a crust, you'll add more oil, which further promotes browning and crisping.

Another technique I employ in this recipe to ensure the crispiest potato crust possible is to par-bake the empty crust on the bottom rack in the oven. Oven rack position when baking is often overlooked, but is a critical player in determining how much food browns. With the bottom of the crust as close to the bottom of the hot oven as possible, the bottom of the crust will brown more quickly. After about 40 minutes, the potato crust turns a deep golden brown and develops a pleasant crunch.

The Filling

The filling for this tart has the best qualities of a quiche filling—it’s creamy, rich, and super flavorful—without being stodgy. The egg custard is rich and silky without overshadowing the fresh spring vegetables it’s paired with. I start by sautéing leeks and asparagus with just a hint of garlic and thyme, so the flavors of the vegetables are still the stars.

Before adding the cooked vegetables into the tart, I layer shredded fontina over the par-cooked potato crust. I love fontina’s nutty flavor, and as it melts while baking, it will form a barrier over the bottom crust, preventing any moisture from the vegetables or egg mixture from seeping into it, keeping the crust as crisp as possible. After the vegetables are spread over the top, tangy crumbled goat cheese and lots of fresh herbs are sprinkled on. Then the whole thing is topped with just enough egg custard to bind the ingredients into a cohesive, sliceable tart. 

The tart is baked once more, with the oven temperature reduced slightly, until the custard just sets (it should still jiggle slightly in the center). The finished tart needs to rest at room temperature for ten minutes before you can slice into it, so the egg filling can further solidify and finish cooking.

Serving Suggestions

This tart is best served right after its brief rest time, when the potato crust is most crisp. As the tart cools, the crust will inevitably lose some of its crunchy appeal, but it will still be delicious. For easier slicing and an impressive presentation, I recommend running a sharp paring knife along the edges of the pan before removing it to ensure the potato crust doesn’t stick. Slide off the edges of the tart pan and you are ready to slice then serve. 

Garnish with more fresh herbs and a dollop of sour cream or crème fraîche and you have a perfect springtime main dish for brunch or lunch.