Place a baking sheet in the oven and preheat the oven to 350 degrees F.
If using a frozen pie crust, thaw, and keep in the fridge until needed.
Put the thawed spinach in a colander and squeeze and drain as much water as possible. Make sure it is very well drained. Set aside.
Slice the mushrooms and sauté over medium high heat in a medium skillet with 1 to 2 teaspoons extra virgin olive oil. Season with salt and pepper. Sauté, stirring frequently, for about 5 to 6 minutes.
Cook bacon and chop into small pieces. Place on paper towels to absorb any excess grease. Try baking bacon or making air fryer bacon.
Remove the pie crust from the refrigerator. If using a frozen pie crust, place the pie tin in a larger pie dish.
In a medium-sized bowl, whisk together the eggs, evaporated milk, ricotta cheese, flour, garlic powder, onion powder, salt, and pepper together until smooth. Stir in the spinach, cheddar cheese, and mushrooms until combined.
Pour the mixture into the prepared pie crust. Arrange the crumbled bacon on top. (The bacon can also be mixed in with the filling if you prefer.)
Carefully place the quiche on the heated baking sheet and bake for 50 to 60 minutes, or until the middle is just set and is no longer jiggly. Let cool for 15 minutes before cutting into pieces and serving.