Triple Cheese French Onion Flatbread Recipe

Flatbread isn't your standard pizza. Usually lighter in toppings and ovular in shape, flatbreads are like pizza's fancy cousin. As the name implies, because most flatbread recipes don't call for yeast the crust is completely flat. Without the yeast, the crust crisps like a cracker, leaving only a hint of the doughy, chewy quality we know in pizza. The blueprint from there is generally the same: A little bit of sauce, some cheese, a collection of toppings, and maybe a hint of seasoning. We've come to expect certain standard toppings for pizza, but flatbread is less hampered by expectations, so you can experiment with different combinations of flavor.

And there's no better way to emphasize that than with the sophisticated flavors of French onion soup. Sweet, deeply caramelized onions sit on top of melted mozzarella, Gruyère, and Parmesan, replicating the flavors of the iconic French dish. A perfect balance between crunchy and gooey, this 3-cheese flatbread created with recipe developer Michelle McGlinn is the perfect excuse to bring some elegance to pizza night.

Gathering ingredients for a triple cheese French onion flatbread

To caramelize onions, you'll just need a few large yellow onions, olive oil, and salt. Keep the olive oil and salt handy to make the base of the flatbread, for which you'll also need flour and water. The remaining ingredients are just cheese, herbs, and seasonings — grab Gruyère, Parmesan, and mozzarella, and shred them fresh for better, meltier results. Then, grab a few sprigs of fresh thyme and some cracked black pepper to complete the flatbread.

Step 1: Heat up a skillet

Heat 2 tablespoons of olive oil in a large skillet over medium heat.

Step 2: Soften the onions

Add the sliced onions and cook until softened, about 5 minutes.

Step 3: Caramelize the onions

Turn the heat to low and add ½ teaspoon salt. Cook until caramelized, adding oil if needed, about 30-40 minutes.

Step 4: Heat up the oven

In the meantime, make your flatbread crust. Preheat the oven to 475 F.

Step 5: Combine the dry ingredients

Add the flour and ½ teaspoon salt to a food processor and pulse to combine.

Step 6: Add the wet ingredients to the dough

Add the remaining 2 tablespoons of olive oil and the hot water and pulse until a ball of dough forms.

Step 7: Knead the dough

Transfer the dough to a lightly-floured surface and knead it until soft and smooth.

Step 8: Roll out the dough

Roll the dough into an oval about ⅛-inch thick.

Step 9: Prepare the crust for baking

Transfer the crust to a baking sheet, prick it with a fork, then brush it with a thin layer of olive oil.

Step 10: Bake the crust until crispy

Bake the crust until crispy and golden brown, about 15 minutes.

Step 11: Add the toppings

Top the crust with the cheeses, caramelized onions, thyme, and black pepper.

Step 12: Bake until melty

Bake the flatbread until melty, about 10 minutes, then slice and serve.

What is the secret to caramelizing onions?

Caramelized onions are a culinary treasure, and for good reason. Truly caramelized onions are delicately sweet, maintaining the characteristic tang of onion flavor without any of the bite. They differ from sweated, softened, and even browned onions, which have a much stronger flavor and different appearance. Because they are slowly cooked for nearly an hour to extract the onion's sugars, the result is deeply browned, super-thin, extremely soft rings of onion: But to get there, you need a few tricks

First, slice your onions as thinly as possible so that they cook faster in the pan. A properly caramelized onion will release its own moisture, not needing much more than the initial few tablespoons of fat. Adding salt at the beginning helps to draw moisture out and to brown the onions faster. But it's important to be patient. Turn the heat to low — or at most, medium-low — and stir occasionally. Don't be tempted to add more oil unless the onions begin burning, in which case your heat is too high and needs to be turned down immediately. There's no quick way to cook great caramelized onions — if you cook them on a higher heat, you won't initiate the Maillard reaction, and you'll get a browned and possibly bitter onion instead. Who knew one vegetable could be so complicated?

How can I customize a French onion flatbread?

This recipe is simple but precise, meant to replicate the familiar flavors of a warming French onion soup. Because of its simplicity, though, it's highly customizable, and it's easy to add, change, or omit toppings to customize this flatbread. The cheese, for example, can be swapped for other varieties, though we recommend sticking with soft white cheeses. Fontina is a great option to replace Gruyére. For a similar tang, you can also replace the Gruyére with Swiss. For a more peppery flavor, replace the Parmesan with Romano. 

To add meat to this vegetarian pizza, try adding cooked and crumbled Italian sausage, prosciutto, or slices of speck. You can also keep it vegetarian and add a variety of sauteed vegetables according to the season, like broccolini, spinach, mushrooms, or even summer squash. To make this rich, creamy flatbread a little spicy, consider adding a sprinkling of red pepper flakes, Aleppo pepper, or even a spoonful of chili crisp after cooking.

Triple Cheese French Onion Flatbread Recipe
4.9 from 11 ratings
A perfect balance between crispy and gooey, this 3-cheese flatbread topped with caramelized onions replicates the sophisticated flavors of French onion soup.
Prep Time
15
minutes
Cook Time
45
minutes
Servings
4
Servings
flatbread pizza on a table
Total time: 1 hour
Ingredients
  • 4 tablespoons olive oil, divided, plus more for brushing
  • 3 large yellow onions, sliced with a mandoline
  • 1 teaspoon salt, divided
  • 1 ½ cups flour, plus more for dusting
  • ½ cup hot water
  • 1 cup shredded Gruyère
  • 1 cup fresh mozzarella, sliced
  • ½ cup shredded parmesan
  • 2 tablespoons fresh thyme leaves
  • ¼ teaspoon cracked black pepper
Directions
  1. Heat 2 tablespoons of olive oil in a large skillet over medium heat.
  2. Add the sliced onions and cook until softened, about 5 minutes.
  3. Turn the heat to low and add ½ teaspoon salt. Cook until caramelized, adding oil if needed, about 30-40 minutes.
  4. In the meantime, make your flatbread crust. Preheat the oven to 475 F.
  5. Add the flour and ½ teaspoon salt to a food processor and pulse to combine.
  6. Add the remaining 2 tablespoons of olive oil and the hot water and pulse until a ball of dough forms.
  7. Transfer the dough to a lightly-floured surface and knead it until soft and smooth.
  8. Roll the dough into an oval about ⅛-inch thick.
  9. Transfer the crust to a baking sheet, prick it with a fork, then brush it with a thin layer of olive oil.
  10. Bake the crust until crispy and golden brown, about 15 minutes.
  11. Top the crust with the cheeses, caramelized onions, thyme, and black pepper.
  12. Bake the flatbread until melty, about 10 minutes, then slice and serve.
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