Leek & Potato Gratin

A layered gratin that works beautifully for Passover or any time you want a comforting vegetable casserole. Sauteed leeks and red bell pepper get combined with sliced baked potatoes, soaked and squeezed matzo, and skim evaporated milk, then topped with mozzarella and chives and baked until golden.

The matzo acts as a binder, almost like a breadcrumb layer in a traditional gratin. Soaking it in hot water softens it, and squeezing out the excess water prevents the casserole from getting soggy. It holds everything together while absorbing the flavors of the leeks and potatoes around it.

Wilting the leeks under a cover before adding the red pepper is a smart step. Leeks take longer to soften than peppers, and covering the pan steams them into silky tenderness without any browning.

Pro Tips

• Squeeze the soaked matzo thoroughly. Any leftover water makes the gratin watery instead of firm and sliceable.
• Use pre-baked potatoes, not raw. They’re already cooked through, so the gratin just needs time to set and brown on top.
• Let the gratin rest 5 to 10 minutes after baking before cutting. It firms up as it cools and holds its shape much better.
• Clean leeks well by splitting them lengthwise and rinsing between the layers. Grit hides in there.

Variations

• Swap mozzarella for Gruyere or Swiss for a more classic gratin flavor.
• Add sauteed mushrooms to the leek mixture for extra depth.
• Stir in a pinch of nutmeg to the evaporated milk for a traditional French touch.