Caramelized Onion, Mushroom and Ricotta Skillet Frittata

Caramelized Onion, Mushroom and Ricotta Skillet Frittata

Balsamic vinegar is the secret ingredient in the caramelized onions, it adds a richness that compliments the sweetness. Dotted with ricotta, the frittata is perfect for a light lunch.

1 hr total time

30 mins active time


Serves 8



  • 4 tbsp (2 oz) unsalted butter


  • 3 yellow onions

    thinly sliced

  • 1 tsp kosher salt


  • 1 tbsp light brown sugar
  • 1 tbsp balsamic vinegar
  • 8 oz baby bella mushrooms


  • 10 large eggs
  • 1 cup (8 fl oz) heavy cream
  • Freshly ground black pepper

    to season

  • 1 tsp fresh thyme leaves
  • 5 oz ricotta cheese


  • 1Before you start, check that your 11-inch cast iron skillet fits in the oven. Melt the butter in the skillet over medium heat. Add the onions and salt and cook, stirring occasionally, for 10 minutes, or until starting to brown. The salt helps draw moisture out of the onions.
  • 2Add the sugar and vinegar and cook, stirring occasionally, for 3 minutes.
  • 3Cook, stirring occasionally, for 5 minutes, or until softened. Set aside in a bowl to cool slightly. Wash and dry the skillet.
  • 4Then add the remaining salt, pepper, thyme and onion mixture and stir to combine.
  • 5Insert the wire rack into position 6. Meanwhile, continue to the next step.
  • 6Place the skillet over medium-high heat and add the remaining butter. Swirl to coat the base and side, this prevents the frittata from sticking.
  • 7Pour the egg mixture into the skillet and crumble the ricotta over the top.
  • 8Once preheated, place the skillet in the oven and start the timer.
  • 9The frittata should be golden brown. If not, give it a bit more.
  • 10Stand for 10 minutes.
  • 11With a salad.