This zucchini quiche is the kind of recipe that earns a permanent spot in your brunch rotation. A store-bought frozen pie crust keeps things weeknight-friendly, while sautéed zucchini, sliced onion, and shredded mozzarella fill it out into something that feels genuinely special. The whole thing bakes in under an hour and works just as well served warm from the oven as it does cold from the refrigerator the next morning.

The Dijon mustard trick is what sets this zucchini quiche apart. A thin brush across the bottom of the crust before filling adds a subtle sharpness that complements the creamy egg filling and keeps the base from going soggy. It takes 30 extra seconds and makes a noticeable difference. If you love a good vegetarian quiche, my Broccoli and Cheddar Quiche uses the same approach with a different filling combination.

Ingredients for Zucchini Quiche

This recipe keeps it simple with ingredients you likely already have on hand:

• Frozen pie crust — A store-bought crust makes this a true weeknight recipe. Marie Callender’s is a reliable option that holds its shape well during blind baking.
• Zucchini — Two medium zucchini, thinly sliced. A mandolin makes quick work of this and ensures even cooking. Summer zucchini from the garden or farmers market work well here.
• Onion — Half a medium onion, thinly sliced and sautéed until softened. It adds sweetness and depth to the filling.
• Eggs — Four large eggs form the custard base. Whisk them well with the milk for a smooth, even pour.
• Whole milk — Whole milk gives the custard a creamy texture without being heavy. Half and half or heavy cream work as richer substitutes.
• Mozzarella — Shredded mozzarella melts into the filling without overpowering the zucchini. A mild provolone or Gruyere are good alternatives for a slightly more complex flavor.
• Dried herbs — Oregano, parsley, and basil add a subtle Italian-inspired note that pairs well with the zucchini.
• Dijon mustard — Optional, but highly recommended. One tablespoon brushed onto the raw crust before filling makes a real difference.

Flavor Upgrade: Dijon Mustard

My pro tip to increase flavor in any quiche is to brush Dijon mustard onto the bottom of the crust. It adds a subtle sharpness that complements the creamy filling. It also helps prevent a soggy bottom. While it’s totally optional, I highly recommend it. You only need about one tablespoon of mustard.

How to Make Zucchini Quiche

Making this zucchini quiche is straightforward, but a few steps make the difference between a good quiche and a great one:

Thaw the crust first. Remove the frozen pie crust from the freezer while you prep the filling. A partially thawed crust is easier to brush with Dijon and holds its shape better going into the oven.

Cook the moisture out of the zucchini. Zucchini releases a significant amount of water when cooked. Sautéing it first in butter with the onion cooks off that excess moisture before it goes into the crust, which is a key step for avoiding a soggy quiche.

Layer, then pour. Add the sautéed vegetables and cheese to the crust first, then pour the egg mixture over the top. This ensures the filling is evenly distributed.

Bake on a sheet pan. Placing the quiche on a rimmed baking sheet catches any overflow and makes it easier to transfer in and out of the oven.

Rest before slicing. Ten to fifteen minutes of resting time after baking lets the custard fully set. A quiche sliced too soon will fall apart.

Recipe Tips for Success

• Use a mandolin to very thinly slice the zucchini for faster, more even cooking.
• Marie Callender’s frozen pie crust holds its shape well and is widely available.
• Tent the quiche with foil and bake in 5-minute increments if it isn’t fully set after 30 minutes.
• This zucchini quiche reheats well. Warm individual slices in an oven at 325 degrees F for 10 minutes or briefly in the microwave.

Serving and Storage

Zucchini quiche works for breakfast, brunch, or a light lunch or dinner. Serve it warm from the oven or at room temperature alongside a simple green salad for a complete meal. It also pairs well with fresh fruit or a cup of soup for a heartier brunch spread.

Storage: Refrigerate leftover zucchini quiche covered for up to 4 days. It slices cleanly cold and reheats well. For longer storage, wrap individual slices in plastic wrap and freeze for up to 2 months. Thaw overnight in the refrigerator before reheating.

Frequently Asked Questions