Preheat your oven to 375°F. Be sure to blind bake the pie crust if the package recommends it.
In a skillet over medium heat, cook the bacon until crisp. Remove and drain on paper towels.
Drain most of the grease from the bacon pan and then sauté the chopped spinach for 1–2 minutes, until wilted.
Layer half the cooked bacon, spinach, and shredded Gruyère cheese evenly in the bottom of the pie crust.
In a medium bowl, whisk together the eggs, half-and-half, salt, pepper, and nutmeg (if using).
Pour the egg mixture over the filling. Top with remaining cheese, spinach and bacon.
Bake the quiche for 35–45 minutes or until the center is set and the top is golden brown. A knife inserted in the center should come out clean.
Let the quiche cool for at least 10 minutes before slicing. Serve warm or at room temperature.