Step 1

Preheat the oven to 375° with a baking sheet on the center rack. Fit the pie crust into a 9-inch pie plate (about 1-inch deep). Fold the edges of the crust under and crimp as desired. Chill in the refrigerator while preparing the filling.

Step 2

Melt the butter over medium heat in a medium skillet. Add the onion and bell pepper. Cook, stirring occasionally, until softened, about 10 minutes. Add the garlic and cook, stirring often, until fragrant, about 2 minutes. Remove from heat.

Step 3

Whisk together the eggs, half-and-half, sour cream, salt, pepper, and nutmeg in a large bowl. Stir in the spinach, cheddar cheese, parmesan cheese, and bell pepper mixture. Pour into the prepared crust.

Step 4

Place the quiche on the preheated baking sheet and bake until it has puffed in the center, is just set, and the crust is golden, 40 to 50 minutes. Transfer the quiche to a wire rack to cool. Serve warm or at room temperature.