Author Notes: There's a lot to love about this quiche, from the clever trick of adding a dollop of both grainy mustard and sour cream to the filling for richness and flavor, to the easy press-in crust made with oats for a nuttier taste. 

Bacon, Leek, and Gruyere Quiche

Makes: one 9" quiche

For the crust

• 1cup quick-cooking oats
• 1cup all-purpose flour
• 1/2teaspoon salt
• 4tablespoons oil (olive oil, vegetable oil, or coconut oil all work)
• 5-6tablespoons cold water, plus more as needed

For the filling

• 4eggs
• 2cups milk
• 2tablespoons sour cream
• 1tablespoon whole-grain mustard
• 1tablespoon butter
• 3-4medium leeks, washed and sliced into thin half moons
• 1/2cup roughly chopped kale
• 2-3strips bacon
• 1cup grated Gruyere cheese (or sub another cheese like Cheddar)
• 1teaspoon fresh thyme
• Salt and pepper to taste

1. To make the crust, preheat the oven to 350 degrees F.
2. In a food processor, pulse together the oats, flour, and salt until the oats resemble flour. Add the oil and pulse a few times, then add the water, starting with the smallest amount (5 tablespoons), and adding more as needed until the dough comes together in a ball.
3. Press the dough in a thin, even layer into a 9" tart or quiche pan with a removable bottom. (You can use a regular pie pan, but I find a tart pan to be easier for slicing the baked quiche.) Press the crust up the sides neatly.
4. Bake the crust for about 10-12 minutes, or until just barely golden brown. Remove from the oven, turn the oven up to 375 degrees F, and let the crust cool while you make the filling. Alternatively, skip the blind baking step and just add the filling — this crust doesn’t require blind baking so it’s up to you!
5. To make the filling, melt the butter in a large pan over medium-high heat. Add the leeks, season with salt and pepper, and cook, stirring occasionally, until the leeks soften. Towards the end of the cooking time, add the chopped kale and cook for another minute until the kale wilts.
6. Chop the bacon into small pieces. In the same pan that you used for the leeks (don't wipe it out), cook over medium-high heat until crispy. Place the bacon onto a paper-towel lined plate and set aside.
7. In a large bowl, whisk together the eggs, milk, mustard, and sour cream. Add the grated cheese, thyme, the cooked leeks and kale, and cooked bacon. Stir to combine.
8. Carefully pour the filling into your prepared quiche crust. I like to place the crust on a baking sheet first and bake it this way, which makes it easier to take in and out of the oven and guards against spillage.
9. Bake the quiche for 45-60 minutes; the quiche should be puffed and golden on the top and the eggs should feel just set all over. Remove from the oven and let cool for at least 15 minutes before slicing and serving.

https://food52.com/recipes/74851-bacon-leek-and-gruyere-quiche