Kale and Cheddar Quiche (Sweet Potato Crust)

This gluten-free quiche uses caramelized sweet potato instead of dough which is a great combination with kale.

5 Tbsp. extra-virgin olive oil, divided
1½ lbs sweet potatoes, peeled, cut into ½" or smaller pieces (~ 4 small)
sea salt
1 large onion, thinly sliced
1 small bunch curly kale, stems removed, torn into bite-size pieces
12 large eggs
4 oz sharp cheddar, freshly grated (~ 1 cup)
1 cup whole milk Greek yogurt
black pepper, freshly ground

Heat 2 Tbsp. oil in a large nonstick skillet over medium. Add potatoes, season with salt and cook, tossing occasionally, until well browned around the edges and just slightly undercooked, 10-12 minutes. Transfer potatoes to spring-form pan and let cool; reserve skillet.

Lightly coat sides of pan with oil. Flatten potatoes slightly with the back of a spoon, packing into the seam where 2 parts of spring-form pan meet.

Preheat an oven to 300°F (150°C/130°C fan, Gas Mark 2).

Heat remaining 3 Tbsp. oil in reserved skillet over medium. Cook onion, tossing occasionally, until softened but not browned, 8-10 minutes. Add kale a handful at a time and cook, stirring, until just softened but not limp, 5-6 minutes. Season with salt. Let cool slightly.

Whisk eggs, cheese, and yogurt in a large bowl; season with salt and pepper. Set springform pan on a parchment or foil-lined rimmed baking sheet. Top potatoes with half of kale and onions, then pour in egg mixture. Gently press remaining kale and onions into surface of egg mixture.

Bake quiche until edges have puffed up slightly and top is just set with no liquid egg remaining, 55-75 minutes. Let cool before slicing.

Makes 8 servings.