Prep the oven and pan. Heat the oven to 400°F (200°C). Lightly grease a 12-cup muffin tin with nonstick spray or butter.

Thaw and roll the pastry. Unfold the puff pastry on a lightly floured surface. Roll it gently into a square about 1/8 inch thick to even it out and extend the edges.

Cut the pastry. Using a knife or pizza cutter, cut the sheet into 12 equal squares. If your pastry is small, you may get 9; re-roll scraps as needed to reach 12 pieces.

Fit into the muffin tin. Press each square into a muffin cup, letting the corners rise up the sides. Don’t worry about perfect shapes; the puff will even out in the oven.

Partially pre-bake (optional but helpful). For a crisp bottom, dock the pastry (poke with a fork) and bake for 5–6 minutes. If the centers puff too much, gently press them down with the back of a spoon.

Make the custard. In a bowl, whisk the eggs, milk or half-and-half, salt, pepper, and garlic powder until smooth. Stir in the herbs.

Add fillings. Sprinkle a little cheese and your chosen mix-ins into each pastry cup. Aim for about 1–2 teaspoons of filling per cup so you don’t overcrowd them.

Pour the egg mixture. Fill each cup until it’s about 3/4 full. The pastry will rise, and you want room for the egg to puff without spilling.

Bake. Return the pan to the oven and bake 12–15 minutes, until the quiches are set in the center and the pastry is deep golden at the edges.

Cool briefly and serve. Let them rest 3–5 minutes in the pan, then loosen the edges with a thin knife and lift them out. Serve warm or at room temperature.