1 small leek, halved lengthwise and cut crosswise into 1/2-inch pieces
1 cup baby spinach
8 large eggs, beaten
Salt and freshly ground pepper
3 ounces fresh goat cheese, crumbled (1/2 cup)
Preheat the oven to 400°. Heat the olive oil in an ovenproof 12-inch nonstick skillet. Add the pancetta and cook over moderately high heat until crisp and brown, about 3 minutes. Transfer the pancetta to a plate and let cool, then crumble it.
Add the leek to the skillet and cook over moderately low heat, stirring, until softened and lightly browned, about 2 minutes. Add the spinach and cook until wilted, about 1 minute. Using a slotted spoon, transfer the leek and spinach to the plate with the pancetta.
Season the eggs with salt and pepper, add them to the skillet and cook for 1 minute. Scatter the reserved pancetta, leek and spinach and the crumbled goat cheese over the eggs and bake for about 4 minutes, until the spinach and goat cheese frittata is set. Slide the spinach and goat cheese frittata onto a cutting board, cut it into wedges and serve at once.