Swiss Cheese & Mushroom Quiche

A French bistro classic that gets its character from two underrated additions: dry mustard and a pinch of thyme. Both stay in the background but sharpen the nutty Swiss cheese so the quiche doesn’t taste flat the way one-note egg pies often do.

The technique to remember is sweating the onions before they meet the mushrooms. Onions release their water first; mushrooms release theirs second. Add them together and the mushrooms steam in onion juice instead of browning. A few minutes of head start for the onions makes a real difference.

Blending the eggs, milk, and flour creates a perfectly smooth custard with no streaks. The flour is doing a quiet job here, stabilizing the custard so it slices clean instead of weeping when cut.

Pro Tips

• Cook the mushroom mixture until almost dry. Wet vegetables turn the bottom crust soggy and pull the custard apart.
• Spread the grated cheese on the crust first as the directions instruct. The cheese acts as a moisture barrier between the custard and the pastry.
• Bake until the center barely jiggles. A solid center means it overbaked and the texture will be rubbery once cooled.
• Let it rest 15 minutes before slicing. The custard firms up as it cools and slices come out cleanly.
• Use a metal pie pan over glass for crispier bottom crust. Glass insulates and slows browning.

Variations

• Stir in chopped cooked bacon or ham for a heartier quiche Lorraine variation.
• Swap the Swiss for Gruyère for a more pronounced nutty, slightly funky finish.
• Add a handful of fresh spinach (squeezed dry) for a Florentine-style quiche.