Best upside down onion tart you'll ever have

Upside Down Onion Tart Recipe

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Here’s my warm, human rewrite of your upside-down onion tart recipe:

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Best upside down onion tart you'll ever have

Best Upside Down Onion Tart You'll Ever Have

A stunning caramelized onion tart with flaky puff pastry that's surprisingly simple to make and bursting with sweet, savory flavor.
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Prep Time 15 minutes
Cook Time 45 minutes
Total Time 1 hour
Servings: 6 servings
Course: Quick & Easy Meals
Cuisine: American
Calories: 285
Ingredients Method Nutrition Notes

Ingredients
  

  • 4 large yellow onions thinly sliced
  • 1 sheet puff pastry thawed if frozen
  • 3 tablespoons butter
  • 2 tablespoons olive oil
  • 2 tablespoons brown sugar
  • 2 tablespoons balsamic vinegar
  • 1 teaspoon fresh thyme leaves
  • 1/2 teaspoon salt
  • 1/4 teaspoon black pepper

Method
 

  1. Preheat oven to 400 degrees Fahrenheit. Line a 9-inch round cake pan or oven-safe skillet with parchment paper.
  2. Heat butter and olive oil in a large skillet over medium heat. Add sliced onions, salt, and pepper. Cook for 20-25 minutes, stirring occasionally, until onions are soft and golden brown.
  3. Stir in brown sugar, balsamic vinegar, and thyme leaves. Cook for another 3-4 minutes until the mixture becomes syrupy and caramelized. Remove from heat.
  4. Transfer the caramelized onion mixture to the prepared pan, spreading evenly across the bottom.
  5. Roll out puff pastry slightly if needed and place it over the onions, tucking the edges down into the pan around the onions.
  6. Bake for 25-30 minutes until the puff pastry is golden brown and puffed up. Remove from oven and let cool for 5 minutes.
  7. Place a large serving plate over the pan and carefully flip the tart upside down. Remove the pan and parchment paper. Serve warm or at room temperature.

Nutrition

Calories: 285kcalCarbohydrates: 28gProtein: 4gFat: 18gSodium: 320mgFiber: 2g

Notes

For deeper caramelization, cook the onions low and slow - don't rush this step as it develops the rich, sweet flavor. Make sure your puff pastry is cold when placing it on the hot onions to ensure maximum puffiness. This tart can be made a few hours ahead and reheated gently in a 300-degree oven for 10 minutes before serving.

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This upside-down onion tart is one of those recipes that looks way more complicated than it actually is. It’s my go-to when I want to impress dinner guests without spending all day in the kitchen. The sweet, jammy onions under that flaky pastry? Pure magic.

In This Recipe hide
1 Best Upside Down Onion Tart You'll Ever Have
1.1 Ingredients 1x2x3x?
1.2 Method
1.3 Nutrition
1.4 Notes
1.5 Tried this recipe?
2 5 Simple Tricks for the Best Upside Down Onion Tart

5 Simple Tricks for the Best Upside Down Onion Tart

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