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Onion tart is a delightful, super easy, healthy, and economical dinner.

With the arrival of colder weather, it is time to get back to comfort food, and as French, we have this category covered.

On the first brink of the first milder morning, my mind rushes to classic bistro dishes. There is something warming and fulfilling to thinking of fall.

Brainstorming thru all the French recipes, I have enjoyed throughout the years, an onion tart stuck with me.

I had plenty of sweet onions on hand. It was only fitting that this would be my first official fall dinner.

I remember my last trip to Paris, sitting on the bistro patio in the quartier of Saint Germain and enjoying a massive slice of onion tart and green salad. Perfect heart and stomach harmony.

Enjoyed for the main dinner or cut into smaller pieces for a quick appetizer,  you will love this recipe.

Origins of French Onion Tart

This savory tart originates from the Alsace region in France. Although it is a cousin to the famous quiche Lorraine, it is not as deep as your traditional quiche.

A quick anecdote is that the bakers used to bake this tart to test the ovens’ heat, and, depending on the time it took to bake it, the oven was hot enough for the bread to be baked.

Difference between a tart and a quiche

Before we continue further, I want to explain why I am calling this tart and not a quiche,

A tart can be either sweet or savory and may not contain a custard filling.  Also, we use the term tart for pies filled with fruits.

A quiche is always savory and has a custard base, eggs, milk, or cream.  You can add more savory ingredients to a quiche, such as ham, cheese, and vegetables, if you wish.

Calling the classic French onion tart, the cream is incorporated with the onions, not the eggs, which form a custard.

This tart is super easy to make and using an already store-bought pie shell; you are left with time to concentrate on the onions.

The onions

The star of this recipe. I know that two pounds of onions may sound so much, but when they are nicely cooked, you will wonder if you have enough of them.

I like and used sweet yellow onions for this recipe as I love its sweetness versus the more intense sharper flavor of the white onions.

This is a personal choice, of course, and if all you have on hand are white onions, save yourself a trip to the store and use them.

They can be used interchangeably, which is just a matter of preference.

Here are a few helpful tips for the ingredients needed 

Pie Crust: You can make your own, but when time is not on your side, our supermarkets have a great selection and the perfect replacement for the homemade.

Onions: I use sweet yellow onions. However, white onions will do as well. I would not recommend using red onions. The flavor changes too much, turning this dish to the sweeter side.

Heavy Cream: when you combine it with the eggs and bake it, it will give you that wonderful custard that makes the tart.

No heavy cream on hand? Use whole milk; you want the richness of it mixed with a couple of tablespoons of all-purpose flour. The milk alone will not solidify as the heavy cream does when baking.

Eggs: Large eggs are used with this recipe. Add an extra egg if you have smaller or medium size eggs.

Emmenthal: the cheese of choice. It can be replaced with Gruyere.

Nutmeg: The secret weapon of this dish. A dash gives that uplifting flavor to the eggs and the onions. You do not want to leave it out.

I enjoy and always purchase the whole nutmeg. Storing it in a glass jar in a dark place will last longer than the powder counterpart. A small grate and you will enjoy this spice in so many dishes.

Cooking tips and step by step to make this fabulous French Onion Tart:

Using minimal ingredients, this tart is very easy to prepare.

One recommendation is to use a ceramic or metal dish to prepare this recipe. Glass will cook faster and tends to burn the crust.

• Start with the onions. Using a mandoline not only saves you time, but it will guarantee that all your onion slices will be evenly sliced.
• Spreading a thin layer of butter into your baking dish, although your pie crust may contain butter already, will prevent it from sticking to your container.
• With the help of a rolling pin, place the pie crust over the pie dish and push down the crust to mold to your pie dish.
• With a fork, lightly poke the bottom of your crust a few times. This step will ensure the steam from being released.
• Your onions need to be cooked at medium-high heat.  If they start to turn brown around the edges, turn down the heat. You want them to sweat, release their natural juices, and become translucent.
• Adding heavy cream and flour to the onions plays an essential role in the flavor of this dish. The flour needs to cook with the onion to become nuttier in taste. The heavy cream will start its cooking process.

The Emmenthal cheese is an optional part of this recipe. I love cheese; therefore, adding it on any occasion I can. You can do without it if you do not have it on hand.

I placed the tart over a cookie sheet to put in the oven and bake. This prevents any spilling from making a mess in your oven.

Can you make this ahead of time?

Yes, you can. This savory dish can be eaten slightly warm the day you bake it. Or brought back to room temperature if you do have leftovers.

If you prepare it a bit warmer, preheat the oven to 320F. Cover with foil and seal the corner. This will allow the steam to stay and not dry out your onion tart. Place it in the oven for about 20 minutes to warm it up.

If you use a ceramic dish, please do not put it from your refrigerator to your oven, as your container will break.

Storage instructions

If you have leftovers, wait until the tart is completely cooled off. Cover with plastic or aluminum foil and place in the refrigerator.

Let it return to room temperature before warming it up or eating it.

If you enjoy this recipe, check out these flavorful recipes:

Caramelized Onion and Bacon Tart

Apple Pie – French Apple Tart or Tarte Normande

Vegetarian Quiche

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