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Low-Carb Caramelized Onion and Kale Frittata

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There’s something about a frittata that makes you want to host a Saturday morning brunch, so go ahead and add this onion and kale frittata to your brunch recipe list.

It’s simple to make, incredibly satisfying, and something the whole family will enjoy. Top it with a little goat cheese, parmesan, or cheddar cheese and some crushed red pepper.

You can also add a pinch of salt and olive oil drizzle for a finishing touch.

This kale frittata is:

  • Savory
  • Delicious
  • Satisfying
  • Flavorful

The main ingredients are:

3 Health Benefits of Onion And Kale Frittatas

#1: May Help Protect Against Disease

Onions, one of the central ingredients in this recipe, are rich in antioxidants and sulfur compounds. Nutrients like these may support disease prevention and help the fight against numerous types of cancer[*][*][*][*][*].

Kale is also known for its nutrient density. A member of the cruciferous vegetable family, kale’s nutrient profile may also protect against cancer. It’s packed with anti-inflammatory and sulfur compounds that may help discourage cancer formation and growth[*][*][*][*].

#2: Supports Heart Health

Eggs are nutrient powerhouses with a complete amino acid profile, plus 6 grams of protein per egg. They also contain the phytonutrients lutein and zeaxanthin, which are excellent for cardiovascular health[*]. Yes, the days of being scared of eggs are over.

Onions may also offer a boost to heart health. They contain an abundance of antioxidants like quercetin and other nutrients like potassium that have been linked to helping reduce blood pressure and increase overall heart health[*][*][*][*][*].

Kale’s antioxidant load is also on the scene. According to some studies, kale may be able to increase your HDL “good” cholesterol levels and decrease your LDL “bad” cholesterol levels[*].

#3: Boosts Brain Power

Eggs are a great source of choline — an essential nutrient for brain function and development. They also contain phytonutrients that may support brain health[*].

Studies show that lutein and zeaxanthin from eggs may contribute to a stronger brain. And even might help in elderly folks with cognitive impairment[*].

Spinach also offers crucial support to your brain health as you age. Nutrients in spinach may help combat oxidative stress in the brain and may even help repair damaged neurological areas after complications such as a stroke[*][*].

Caramelized Onion and Kale Frittata

This frittata only takes about 25 minutes to make. You can even prep it ahead on the weekend so you have a healthy keto breakfast all week.

Preheat your oven to 350 degrees Fahrenheit and coat your pie pan or cast iron skillet with a little butter or non-stick spray.

Pull out your cutting board and chop your onion and kale to desired bite-size pieces.

Grab a large pan and place it on your stove over medium heat and melt your butter. Once the butter melts, toss in your onions, sea salt, and a dash of black pepper. Cook for roughly 7-10 minutes on medium-high heat, or until the onions are caramelized and golden brown.

Side note: if the pan starts to get a little dry while you’re caramelizing your onions, add some water to prevent any burning.

Add your kale to the mix and cook it with the onion mixture for three-ish minutes until it begins to wilt, then remove the pan from the heat and allow the entire mixture to cool slightly.

While the mixture is cooling, grab a large bowl or high-speed blender and add in the eggs, milk, sea salt, and black pepper, blending on high until the mixture becomes frothy.

Add the onion and kale mixture to the prepared pie pan and gently pour the egg mixture over the top of the kale mixture, like a blanket.

For a truly dairy-free frittata, use coconut oil or avocado oil in place of the grass-fed butter and unsweetened almond milk in place of the dairy milk.

Bake for 25 minutes or until the top of the frittata is a lovely golden brown and the eggs are set. Enjoy!


Caramelized Onion and Kale Frittata

Onion and Kale Frittata

This onion and kale frittata is perfect for any weekend brunch or meal prep. Make it ahead on a Sunday night so you’ll have breakfast ready all week!

  • Author: Corina Nielsen
  • Total Time: 25 minutes
  • Yield: 4 large slices 1x


  • 1 large yellow onion (thinly sliced)
  • 2 tablespoons grass-fed butter
  • 1 cup kale of choice
  • 1/4 cup water
  • 3/4 teaspoons salt
  • 1/4 teaspoon ground pepper
  • 8 large eggs
  • 1/2 cup unsweetened milk or cream of choice


  1. Heat a large pan over medium heat and melt butter. Add sliced onions, 1/2 teaspoon salt, and a pinch of pepper.
  2. Cook onions for 7-10 minutes until cartelized and golden brown. Add a few tablespoons of water at a time if pan gets dry to prevent burning.
  3. Add kale and cook with onions for 2-3 minutes until wilted. Remove pan from heat and let cool.
  4. Preheat oven to 350°F and coat a 9-inch pie pan with non-stick spray or butter.
  5. Add eggs, milk, 1/4 teaspoon of salt, and a pinch of pepper to a high-speed blender or large bowl. Mix well until light and fluffy.
  6. Add onions and kale to prepared pan in an even layer. Pour egg mixture onto onions. Bake for 25-30 minutes until top is golden brown and eggs are just set.
  7. Option to add shredded cheese for even more flavor.


  • Serving Size: 1 slice
  • Calories: 173
  • Fat: 12g
  • Carbohydrates: 3g (2g net)
  • Fiber: 1g
  • Protein: 13g

Keywords: Onion and Kale Frittata


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