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Caramelized onion frittata in a grey cast iron pan

Caramelized Onion Frittata

  • Author: Kathryn | Urban Foodie Kitchen
  • Prep Time: 10 min
  • Cook Time: 20 min
  • Total Time: 30 minutes
  • Yield: 4-6 servings 1x
  • Category: Breakfast + Brunch
  • Method: Oven Baked
  • Cuisine: Italian


This frittata gets an added flavor boost with a good dose of caramelized onions, making it a big hit for weekend brunches as well as special occasions.


  • 8 large eggs
  • 1/4 cup milk (1% or higher)
  • 1 tablespoon dijon mustard
  • 1/2 cup shredded swiss cheese
  • 1 cup caramelized onions*
  • 1 teaspoon dried sage
  • 1/2 teaspoon ground pepper
  • 1/4 teaspoon salt
  • 1 cup baby arugula or microgreens
  • shredded swiss cheese for serving


  1. Preheat the oven.  Move the rack to the middle position on the oven and preheat to 400°F.  Coat a 10-12″ oven-safe skillet with olive oil spray.
  2. Blend the ingredients.  Whisk the eggs, milk, mustard, sage, salt and pepper together in a large mixing bowl until well blended.
  3. Assemble the frittata. Add the onions and cheese to the prepared pan. Pour in the eggs.
  4. Bake the frittata. Put the pan in the oven and bake until the eggs are set, 8 to 10 minutes. To check, cut a small slit in the center of the frittata. If raw eggs run into the cut, bake for another few minutes; if the eggs are set, pull the frittata from the oven. For a browned, crispy top, run the frittata under the broiler for a minute or two at the end of cooking.
  5. Cool.  Let the frittata cool in the pan for 5 minutes, top with baby arugula or microgreens and a bit of extra shredded cheese, then slice into wedges and serve.


  1. Total time assumes you make the caramelized onions prior.  If you are making them at the same time, add about 60 minutes to your total time and make the onions before starting the rest of the frittata.
  2. Leftover frittata can be stored in an airtight container in the refrigerator for 3-4 days.

Keywords: Sunday brunch,