French Onion Tart


Finished-Slice-1-of-1-400x265With tomatoes practically falling off the vines, this is the perfect time to make a French Onion Tart. When I had the take out shop, this was a huge hit.  We also made them in half sheet pans, trimmed the edges, cut them into 1 1/2 squares for appetizers.  This tart is an example of savory pastries which are as much a part of baking and pastry as sweet.

The crust is as easy to make as falling off a log.  While the recipe gives instructions for the food processor, it is just as easy to make in a mixer putting all the dry ingredients in the bowl and the wet ingredients on top. After making the dough it needs to rise.  After it rises you can punch it down and refrigerate it for the next day.  When ready to use,  just push it out into the pan and up the sides.  I definitely suggest refrigerating it while you prepare the filling as you don’t want it to rise at this point.  It bakes up beautifully browned and crisp with great flavor.

Fresh basil is essential for this French Onion Tart to come to life.  Whenever I use fresh herbs in a baked item, I bury them under other ingredients so they retain maximum flavor.  If they are sprinkled on top, they will just dry out, so you might as well use the dried version to start.

If the yeast crust has not been done ahead of time, start it first.  I start the onions next since they take a bit of time.  The next step is to start prepping the tomatoes, olives, and basil.  After the onions are finished, cool them to lukewarm.  Assemble, bake, wait a few minutes then cut the French Onion Tart for a phenomenal food experience. This is good, hot, warm or room temperature.  

Tart Crust

Crust ingred.

1/2 teaspoon yeast
2/3 cup water, 100 degrees
1 teaspoon olive oil
1 teaspoon salt
1 1/2 cups all-purpose flour (210 grams)

Combine yeast with water.  Yeast Dissolving in waterStir to dissolve yeast.  Add oil. Oil in Yeast/waterAdd the flour and salt to a processor bowl.  Dry Ingredient in processorProcess briefly to mix. With the machine running pour the yeast water down the feedtube. Pouring down feed tube Process until a ball forms and then for 30 seconds.Balled up in processor

Dump the dough out on a lightly floured board

Out of processor (1 of 1)

Knead into a smooth ball.  Balled up on tablePlace in a sprayed bowl, turn to coat both sides, cover with plastic wrap and let rise until doubled.  At this point, it may be refrigerated overnight if desired.Dough in bowl

French Onion Tart Filling

Tart ingredients

1 pound  (454 grams) Spanish Onions
3 tablespoons olive oil
4 teaspoons plain or grainy dijon mustard
4 ounces (114 grams) grated Guyere cheese
1 pound (454 grams) roma or plum tomatoes or any small tomato
7 kalamata olives, seeded/halved
1 tablespoon shredded fresh basil or more to taste
Coarse Black Pepper to taste
Salt as needed
Garlic oil, as needed
2 tablespoons minced parsley

Preheat oven to 375 degrees.

Slice onions thinly into half-moons. cutting onion in half

Sliced in half

Pile of Sliced onions

Heat oil in a pan. Oil in pN Add the onions.  Turn in the pan to coat onions with oil. Onions in panSaute over medium heat until deep golden brown.Onions browningOnions browning 3

Onions browning 4

Caramelized Onions for French Onion tart

Lower heat as onions start to color.  It takes approximately 45 to 60 minutes for them to cook.    If they get too dry before they are done, add a bit more oil.  Cool onions.

Punch dough down.   Press dough into the bottomCrust in pan

Pressing Crust in

and up sides of a sprayed 9” quiche pan with removable bottom. Pressing Crust up sides

Crust Pressed in for French Onion Tart

Place in refrigerator while finishing tart.

Cut tops off tomatoes. Squeeze the tomatoes to remove most of the juice but do not distort the tomato.Juicing Tomato for French Onion tart

and cut in half.Tomatoes cut in half (1 of 1)

Cut each half into wedges.

Cutting tomatoes

Pile of Tomatoes, cu

Set aside.

Spread the mustard over bottom of the crust. Dijon onSprinkle with basil.Basil onTop with onions,Onions on then cheese. Cheese on Arrange tomatoes in a flower pattern. Tomatoes on

Tomatoes on whole tart

Sprinkle with olives, 1/2 teaspoon salt, and 1/4 teaspoon pepper.


Bake at 350°F for approximately 40 to 45 minutes until the crust is a medium golden brown.  Brush with garlic oil.Brushing oil on crust

If the top appears to have lots of juice, blot with a paper towel.Blotting Baked Tart

Sprinkle with parsley just before serving.

Parsley on French Onion Tart

Release the tart from the pan by placing it on a fat can.  The side should drop down.Tart on canTransfer to a serving dish with two wide spatulas or pancake turners.  Our name for these were “lifter-uppers.”Lifter uppers transferring tart

This can be made the day ahead, cooled and refrigerated.

This French Onion Tart should be served warm or at room temperature.  To reheat microwave for 20 to 30 seconds per piece.  To reheat whole, place in a 375°F oven for about 20 minutes. Brush with garlic oil and sprinkle with parsley before cutting and serving.Finished French Onion Tart

If you enjoyed this Savory Tart, see

Goat Cheese Tart

Torta Rustica

International Flatbreads


Pastry has not only been my profession, but my passion. If there is anything in particular you would like to see or any questions about baking or pastry, please let me know. Be sure to subscribe so you don't miss a post!
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4 thoughts on “French Onion Tart

  1. Helen S. Fletcher Post author

    I am so glad you enjoy this. It is one of my favorite savory tarts.
    Even more glad you are looking in on my blogs.

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