Preheat the oven to 375F and blind bake the pie crust, by baking for 15 minutes with weights and then 5 minutes without weights until lightly golden in color. Lower the heat to 350F afterward for the quiche.
While the crust is baking, in a saucepan over medium heat, add the oil and onion and cook for about 5-6 minutes.
Add the peppers and garlic. Continue to cook until the peppers have softened, or about 5 minutes.
Add the spinach and cook for 2 more minutes.
In a separate bowl, whisk together the eggs and the half-and-half until combined.
Once the pie crust has been blind-baked, spread the grated cheese on the pie crust. Add the pepper and onion mixture, followed by the egg mixture.
Bake the quiche at 350F for 35 minutes, or until the custard starts to darken.