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Asparagus Frittata with Prosciutto and Caramelized Onions

Servings: 4 to 6

This colorful frittata makes a perfect brunch entrée, especially when paired with Radish, Celery & Frisée Salad. A little baking soda added to the onions helps them to brown faster.


  • 5 Tbs. unsalted butter
  • 1 lb. sweet onions, finely sliced (about 3-1/2 cups)
  • 1/8 tsp. baking soda
  • 1/2 tsp. sherry or red-wine vinegar
  • 10 large eggs
  • 2 Tbs. olive oil
  • 1 medium or 2 small leeks, trimmed, white and tender greens sliced 1/4 inch thick and thoroughly rinsed (about 1-3/4 cups)
  • 4 oz. prosciutto, coarsely chopped
  • 1 Tbs. finely chopped fresh flat-leaf parsley
  • 2 tsp. whole-grain Dijon mustard
  • Kosher salt and freshly ground black pepper
  • 10 spears asparagus, preferably medium, trimmed


  • Position a rack in the center of the oven, and heat the oven to 400°F.
  • In a large heavy-duty saucepan, melt 3 Tbs. of the butter over medium-high heat. Add the onion, raise the heat to high, and cook, stirring occasionally, until beginning to brown, about 5 minutes. Add 2 Tbs. water and the baking soda, and continue to cook, stirring occasionally, until the liquid has evaporated. Add more water 2 Tbs. at a time as needed until the onions are deep golden brown, about 8 minutes. Add the vinegar, and cook for another 30 seconds. Set aside to cool.
  • Meanwhile, beat the eggs in a large bowl.
  • Heat 1 Tbs. of the butter and 1 Tbs. of the oil in a large nonstick skillet over medium-high heat. Add the leeks and cook, stirring occasionally, until browned in spots, about 5 minutes. Let cool briefly, then transfer the leeks to the bowl with the eggs. Add the onions, prosciutto, parsley, mustard, 1/2 tsp. salt, and 1/2 tsp. pepper, and stir to combine.
  • Heat the remaining 1 Tbs. butter and 1 Tbs. oil in the same skillet over medium heat. Pour in the egg mixture; if necessary, use a fork to distribute the ingredients evenly. Lay the asparagus spears across the top. Bake until set, 15 to 17 minutes. Allow to rest for 5 minutes. Using a thin spatula, slide the frittata onto a serving dish, and cut into wedges.


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Reviews (4 reviews)

  • annaostlind | 04/06/2020

    This was amazing.. will make again

  • annaostlind | 04/06/2020

    This was amazing! It was time consuming but so good! Will make again!

  • fuzzycat | 01/03/2019

    Did not love this recipe. Given the 4 oz prosciutto the added salt made it too salty. A bit time consuming, did not seem worth the trouble.

  • cookingannie | 12/21/2018

    a favorite

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