Preheat oven to 375°F (190°C). Line a baking sheet with foil.

Arrange frozen quiches in a single layer; brush tops lightly with oil or butter.

Bake 12–16 minutes until heated through and edges are golden.

Let rest 2 minutes, then transfer to a platter. Offer mustard in a small bowl for dipping.

Garnish with parsley and provide toothpicks for easy grab-and-go.