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Round onion frittata with a golden top and one wedge cut, in a skillet on a wooden board beside parsley

Frittata di Cipolle with Parmigiano and Sweet Onions

Frittata di cipolle sets slow-cooked onions in eight eggs and Parmigiano, then finishes in a 180 C / 350 F oven for a tender center that slices cleanly.
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Prep Time 15 minutes
Cook Time 37 minutes
Total Time 57 minutes
Servings: 4 servings
Course: Light Main Course
Cuisine: Italian
Calories: 250
Ingredients Method Notes

Ingredients
  

For the onions
  • 700 g yellow onions (about 3 large); halved and sliced 3 mm thick
  • 3 tbsp extra-virgin olive oil (45 ml)
  • 1/2 tsp fine sea salt
  • 1 tbsp water only if the pan looks dry
For the eggs
  • 8 large eggs
  • 50 g Parmigiano Reggiano (about 1/2 cup); finely grated
  • 2 tbsp flat-leaf parsley finely chopped
  • 1/2 tsp fine sea salt
  • 1/4 tsp black pepper freshly ground

Method
 

  1. Heat the olive oil in a 26 cm / 10-inch oven-safe nonstick skillet over medium-low heat. Add the sliced onions and 1/2 tsp salt, and cook for 25 minutes, stirring every 3 to 4 minutes, until they're soft and glossy and pale gold at most. If the edges start to brown, lower the heat and stir in 1 tbsp water.
  2. While the onions cook, heat the oven to 180 C / 350 F with a rack in the middle. Whisk the eggs, Parmigiano, parsley, remaining 1/2 tsp salt, and pepper in a large bowl until no streaks of white remain.
  3. Spread the onions in an even layer and drop the heat to low. Pour the eggs over the onions and tilt the pan so the eggs flow through. Cook for 2 minutes without stirring, until the edges just begin to set.
  4. Slide the skillet onto the middle rack and bake for 10 minutes, until the center doesn't jiggle when you nudge the pan and the top is lightly golden. An instant-read thermometer in the center reads 160 F / 71 C.
  5. Set the skillet on a trivet and drape a towel over the hot handle. Rest the frittata for 5 minutes, then run a silicone spatula around the edge, slide it onto a board, and cut it into 4 wedges.

Notes

  • Cook the onions the full 25 minutes, since they shrink to roughly a third of their raw volume.
  • Wrap a towel around the skillet handle after baking so nobody grabs it hot.
  • Let the frittata rest 5 minutes in the pan before cutting so the wedges hold together.
  • Taste the Parmigiano before salting the eggs, since aged cheese varies in saltiness.