Onion, Cheese & Bacon Quiche

This quiche is built on a foundation of deeply caramelized onions, and that hour of low, slow cooking is what separates it from every other onion quiche you’ve tried. Two full pounds of yellow onions cook down in butter over very low heat until they’re golden, jammy, and intensely sweet. That patience is the recipe’s secret.

Sprinkling flour over the softened onions and cooking for another three minutes creates a light roux that prevents the custard from being watery. The onions go into the partially baked pastry shell first, then crumbled bacon gets scattered on top, the egg-cream custard pours over, and grated Swiss cheese finishes the top.

Nutmeg in the custard is a classic Alsatian touch. Just a pinch adds a warm, spicy note that sits behind the onion sweetness and bacon saltiness without calling attention to itself. Baking in the upper third of the oven ensures the top browns and puffs beautifully while the custard sets underneath.

Chef Tips

• Cook the onions for a full hour on very low heat. This is not optional. Rushing on higher heat browns them unevenly and produces bitter spots instead of sweet caramelization.
• Stir occasionally, not constantly. The onions need contact time with the hot pan to develop color. Too much stirring slows the caramelization.
• Use a partially baked pie shell. A raw crust will be soggy and undercooked on the bottom. Par-baking firms it up before the wet custard goes in.
• Bake in the upper third of the oven for the best top browning. The quiche should puff and turn golden brown.

Variations

• Gruyere instead of Swiss for a nuttier, more complex cheese flavor that’s traditional in Alsatian quiche.
• Add fresh thyme to the onions during the last 10 minutes of caramelizing for an herbal layer.
• Mushroom addition: Sauté sliced mushrooms and layer them with the onions for a more substantial filling.