Cook veggies. Add oil (2 tablespoons) to a large skillet over medium heat. Add chopped onion (2 cups) and cook until translucent - about 8 minutes. Add minced garlic (2 cloves), and cook until fragrant - 1-2 minutes. Add spinach (10 ounces) in batches. As the spinach wilts and releases it's liquid, you'll be able to add more. Add salt (1/2 teaspoon) and crushed red pepper (1/4 teaspoon). Set veggies aside and allow them to cool slightly.
Assemble. In a large bowl, whisk together the eggs (6 large size), heavy cream (1/4 cup), and remaining salt. Stir in the shredded mozzarella (1 1/2 cups ) and veggies. Pour contents into the prepared pie pan.
Bake + enjoy! Bake quiche for 20-25 minutes. The quiche is done once the edges begin to brown and the center is firm. Allow the quiche to cool for 10 minutes before cutting. Then DIG ON IN!
Notes
Mild Tasting Oil. You want an oil with a high smoke point and mild flavor -- think avocado, vegetable, safflower, sunflower, peanut. Skip EVOO, coconut, or sesame oil.
Spinach. You can swap the fresh for 10 oz frozen spinach -- Just be sure to thaw and thoroughly drain the spinach before adding it in (you want to remove as much liquid as possible).
Nutritional information is based on 1 slice, if you slice this quiche into 8 slices: