Preheat your oven to 190°C (375°F). Lightly butter or spray each cup of a muffin tin to prevent sticking.
Roll out the pastry sheet on a lightly floured surface until it's about 1/8 inch thick. Using a pastry cutter or glass, cut out circles roughly 3 inches in diameter.
Gently press each pastry circle into the muffin cups, fitting snugly against the sides. Chill the tin in the fridge for about 10 minutes to help set the crust.
In a mixing bowl, whisk together the eggs and heavy cream until smooth and slightly frothy, about 1 minute. Season with a pinch of salt and pepper.
In a small pan, sauté diced onion or spinach until tender, about 3-5 minutes. Let cool slightly before adding to the filling.
Place small spoonfuls of cheese, cooked vegetables, and bits of ham into each pastry-lined cup, filling about three-quarters full.
Pour the egg mixture evenly over each filled pastry, filling each cup almost to the top, but leaving a small gap to prevent spilling.
Bake in the preheated oven for 20-25 minutes, until the tops are golden brown and puffed, and a toothpick inserted in the center comes out clean.
Once baked, remove the muffin tin from the oven and let the mini quiches rest for 5 minutes. They will be tender and slightly puffed with crisp edges.
Gently loosen the quiches with a knife or spatula and transfer them to a plate. Garnish with chopped herbs for a fresh touch.
Enjoy these warm or at room temperature—perfect for a quick breakfast, brunch, or make-ahead snack that always delights.
