Preheat the oven to 400ºF. Wash the sweet potato and poke it a few times with a fork. Wrap tightly in aluminum foil and place on a baking sheet in the oven for one hour, or until it gives easily when gently squeezed with a potholder.
Allow the sweet potato to cool slightly before scooping out the flesh into a bowl. Add the water and mash with a fork. Alternatively you could puree it in a small food processor or use an emulsion blender to puree it in the bowl.
While the sweet potato is cooking, prepare the crust. Grease a 9 inch pie pan with olive oil. In a medium bowl, stir together almond meal, garlic, dried thyme, salt, and black pepper to taste. Add in olive oil and 1 tablespoon plus 1 teaspoon water and stir until thoroughly combined.
Press the crust evenly into the bottom and sides of the prepared pan. Transfer to the oven next to the sweet potato and bake until lightly golden and firm to the touch, 15-20 minutes.
To prepare the filling, heat 2 teaspoons olive oil in a large pan over medium heat. Add the spinach and stir for 2 minutes, or until wilted and most of the moisture is out of the pan. Remove from the heat and allow to cool slightly. In a large bowl, whisk together eggs, milk, 1/2 teaspoon salt, and crushed red pepper flakes. Add most of the parmesan cheese and the cooled spinach and stir to combine.
Pour the egg mixture carefully into the baked crust. Add the sweet potato in about 5 dollops, using a spoon or knife to carefully settle it into the egg mixture and swirl slightly. Top with the remaining parmesan cheese.
Transfer the quiche to the oven and bake until the center is firm and cooked through, 30-33 minutes. Let cool 5-10 minutes before slicing into wedges and serving.
Nutrition information is for 8 servings.A few ideas for how to customize your sweet potato and spinach quiche:
Replace the sweet potato with other vegetables such as butternut squash, diced red potato, or zucchini, adjusting cooking times as necessary
Swap the spinach for other leafy greens such as kale, bok choy, or mustard greens
Come up with fun combinations of veggies like spinach artichoke fontina, tomato onion feta, or corn jalapeño cheddar, trying to keep the measurements roughly the same and adjusting cooking times on the veggies as necessary
Use your favorite store bought crust and/or puree for a quick and easy meal