Step 1

Preheat oven to 375 degrees F (190 degrees C).

Step 2

Fit pie crust into a 9-inch pie dish.

Step 3

Melt butter in a large skillet over medium heat; cook and stir green onions and garlic until green onions are softened, about 5 minutes. Cook and stir turkey bacon in the green onion mixture until fragrant.

Step 4

Stir spinach, shiitake mushrooms, and broccoli into green onion mixture; cook and stir vegetables until softened, 5 to 7 minutes. Mix in 1/4 cup Cheddar cheese.

Step 5

Spoon vegetable mixture into the pie crust.

Step 6

Beat eggs, milk, sea salt, and black pepper together in a bowl; pour egg mixture gently over vegetable filling, slightly stirring eggs into the filling to combine.

Step 7

Bake in the preheated oven for 15 minutes; sprinkle 1/2 cup Cheddar cheese over the top of the quiche and bake 10 additional minutes. Cover quiche with aluminum foil and bake until quiche has set and a toothpick inserted into the quiche comes out clean, about 10 more minutes.

Step 8

Allow quiche to cool for 5 minutes before serving.