Prep the oven and pan: Heat the oven to 375°F (190°C). Lightly grease a standard 12-cup muffin tin with nonstick spray.

Prep the crust: On a lightly floured surface, roll the pie dough to about 1/8-inch thick. Use a 3-inch round cutter (or a glass) to cut 12 circles. Press each circle into the muffin cups, letting the dough come slightly up the sides. Prick the bottoms a couple of times with a fork.

Quick blind bake: Bake the crusts for 7–8 minutes until just set but not browned. This helps prevent soggy bottoms. Set aside to cool slightly.

Sauté the aromatics: Warm the olive oil or butter in a skillet over medium heat. Add the onion and cook until soft, 3–4 minutes. Stir in the garlic and cook for 30 seconds until fragrant.

Wilt the spinach: Add the spinach to the pan. Cook, stirring, until just wilted and most moisture evaporates, 2–3 minutes. If using frozen spinach, add it drained and cook until dry. Remove from the heat and let cool for 2 minutes.

Make the custard: In a bowl, whisk the eggs, milk, and cream until smooth. Season with salt, pepper, and a pinch of nutmeg. Stir in herbs if using.

Fill the cups: Divide the spinach-onion mixture among the crusts. Sprinkle feta evenly over the spinach. Pour the egg mixture on top, filling each cup about 3/4 full. Give the pan a gentle shake to level.

Bake: Place the tin on the center rack and bake for 16–20 minutes, until the centers are just set and slightly puffed. A slight jiggle is okay; they’ll finish setting as they cool.

Cool and release: Let the quiches rest in the pan for 5 minutes. Run a thin knife around the edges and lift them out. Serve warm or at room temperature.

Finish with freshness: For extra brightness, top with a sprinkle of chopped dill or a squeeze of lemon just before serving.