Preheat oven to 375°F (190°C). Grease a 6-cup muffin tin or line with parchment rounds.

Lightly flour a work surface and unfold the puff pastry. Roll briefly to smooth creases if needed. Cut into six roughly equal squares or circles to fit the muffin cups.

Gently press each piece into the cup, forming a small shell. Optional: prick the bottoms lightly with a fork.

Blind-bake shells for 5 minutes to help prevent sogginess.

Heat a small skillet over medium heat with a teaspoon of oil or butter. Add chopped spinach and sauté for 1–2 minutes until just wilted.

Transfer the wilted spinach to a sieve and press or squeeze out excess moisture.

In a bowl, whisk the eggs with the heavy cream until smooth. Stir in the shredded cheddar, grated Parmesan, nutmeg, salt, and pepper. Fold in the drained spinach.

Reduce oven to 350°F (175°C) if shells were blind-baked at a higher temp.

Divide the filling evenly among the six pastry cups, filling to about 3/4 full.

Bake for 18–22 minutes or until the centers are set and pastry edges are golden brown.

Rotate the pan halfway through for even browning.

Let the mini quiches cool for 5 minutes in the tin, then transfer to a rack.

Garnish with chopped parsley or thyme before serving.