Caramelized Onion Flatbread

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This Caramelized Onion Flatbread puts a spin on Alsatian Pizza and makes for the perfect pre-dinner bite.

Caramelized Onion Flatbread from (@whatsgabycookin)


Many moons ago when I was the pickiest eater on the planet, I vividly remember going to France one summer with my family and not eating ANYTHING besides Alsatian Pizza. It's basically just a pizza loaded with tons of caramelized onions and gruyere cheese! Occasionally there's bacon too because that just feels right! It's incredible and makes for an excellent first course / snack / appetizer that feeds a crowd. It's rich and decadent but don't take much time to make other than the caramelized onions.

Caramelized Onion Flatbread from (@whatsgabycookin)

For this Caramelized Onion Flatbread, my take on the Alsatian Pizza, I went with a puff pastry flatbread - easy, all the gruyere and fontina cheese, plenty of those sweet caramelized onions and prosciutto! Three of my favorite foods- think french onion soup version of flatbread!!

The puff pastry makes it bit airier than pizza and the prosciutto is a bit lighter than bacon! All in all, it's the perfect snack! Grab a bottle of red or white wine and it's dinner party material!

Caramelized Onion Flatbread from (@whatsgabycookin)

Caramelized Onion Flatbread

Author: Gaby Dalkin
5 from 3 votes
My take on that incredible Alsatian Pizza that dominates France but instead of a pizza crust - PUFF PASTRY!!
Prep Time 10 minutes
Cook Time 45 minutes
Total Time 55 minutes
Course Appetizer
Cuisine French
Servings 6 people


  • 1 package frozen puff pastry, thawed. (17.5 ounce)
  • 2 large yellow onions (about 1 pound), peeled and sliced into ¼ in slices
  • 2 tablespoons unsalted butter
  • 3 tablespoon olive oil, divided
  • Kosher salt and freshly cracked black pepper to taste
  • 1 teaspoon fresh thyme, leaves only
  • 4 ounces gruyere cheese, shredded
  • 4 ounces fontina cheese, shredded
  • 4-6 sliced prosciutto
  • freshly grated nutmeg


  • Heat butter and 1 tablespoons of olive oil a large dutch oven over medium high heat. Add in the sliced onions and season with salt and pepper. Cook, stirring occasionally, for 15 mins uncovered. Reduce heat to medium and cook another 10 minutes stirring frequently. Drop heat to medium low and continue to cook till onions are deep golden brown another 5-10 minutes. Stir in thyme leaves and remove from heat. Place in a bowl to cool.
  • Preheat oven to 400 degrees F.  Adjust oven racks to upper and lower thirds of the oven. Line two baking sheets with parchment paper.
  • Combine both cheeses and diced prosciutto in a bowl.
  • Remove the thawed puff pastry from the refrigerator and on a lightly flowered surface roll each piece out to a 9x14 rectangle
  • Place each piece of puff pastry on its own baking sheet and poke all over with a fork. Cover with another piece of parchment , followed by a piece of foil and place another baking sheet on top of the foil covered puff pastry to prevent it from getting too puffy.
  • Bake in the oven for 15 minutes; remove the top sheet pan along with the parchment and foil. Continue to cook another 5-8 minutes until it’s golden brown, you can flip it over at the point if you notice the bottom is darker. Remove from the oven.
  • Drizzle each flatbread with olive oil and spread with ½ of the onion mixture, sprinkle each with ½ of the cheese and prosciutto mixture, put back into the oven and cook 5 minutes until cheese is melted and starts to brown in spots.
  • Remove from oven, sprinkle with fresh nutmeg, salt and pepper. Cut into desired pieces and serve hot from the oven.


Using puff pastry makes this a really light type of pizza which is perfect for a small bite before the main meal.

Nutrition Information

Calories: 720kcal | Carbohydrates: 42g | Protein: 17g | Fat: 54g | Saturated Fat: 19g | Polyunsaturated Fat: 6g | Monounsaturated Fat: 27g | Trans Fat: 0.2g | Cholesterol: 53mg | Sodium: 497mg | Potassium: 155mg | Fiber: 2g | Sugar: 3g | Vitamin A: 486IU | Vitamin C: 4mg | Calcium: 317mg | Iron: 2mg
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  1. 5 stars
    This was AMAZING! The ingredient list sounds delicious on its own, but all together it is magical. 10/10 would recommend

  2. 5 stars
    Oh my this looks amazing. I knew there was a recipe waiting for all my over wintered onions!! I LOVE this!

5 from 3 votes (1 rating without comment)

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