ONIONS & SPINACH: Caramelized Onions and Roasted Spinach

Why onions?

Onions are a member of the alliaceous family (along with garlic, leeks, shallots and chives).  “The sulfur compounds of this family…reduce the carcinogenic effects of nitrosamines and N-nitroso compounds, which are created in overgrilled meat and during tobacco combustion. They promote apoptosis (cell death) in colon, breast, lung, and prostate cancer, as well as in leukemia.” (David Servan-Schreiber, Anti-Cancer, page 123).

Why spinach?

“…all the bright-colored fruits and vegetables (orange, red, yellow, green) contain vitamin A and lycopene, which have the proven capacity to inhibit growth of cells of several cancer lines, including brain gliomas.” (David Servan-Schreiber, Anti-Cancer, page 122).


The process of slow roasting the onions and spinach cooks down the veggies so that each spoonful of cooked veggies is equal to about THREE spoonfuls of raw veggies! This means that you can sneak a lot of veggies into your meals by adding just a few tablespoons of these great roasted veggies!

Here are a few of the foods to which I often add caramelized onions or roasted spinach – or both:

  • Hummus
  • Rice
  • Beans
  • Quinoa
  • Cottage cheese
  • Egg whites (Just add this mixture to the recipe for Egg White Puffs)
  • Soups (Just mix into almost any soup!)
  • Pasta sauce

Also, the mixture of caramelized onions and roasted spinach makes a great side dish for chicken, fish, or grass-fed lean beef. For more flavor, just add any herb and spice combination that you like – even just a dusting of freshly ground black pepper and a pinch of salt!


  • 2 pounds red (or yellow) onions, chopped
    • After posting this recipe calling for yellow onions, I tried it with red onions, and found that it was even better with red onions.
    • I didn’t specify organic onions. That’s because, of all vegetables and fruits, regular (non-organic) onions have the least pesticide residue, according to the Environmental Working Group.
  • 2 pounds frozen chopped organic spinach
    • I specified organic spinach. That’s because regular (non-organic) spinach comes with a fair load of pesticides, according to the Environmental Working Group.
    • Whole Food’s 365-Brand frozen Organic Chopped Spinach is the frozen organic spinach that I use most often.
    • I don’t bother with fresh organic spinach for this recipe because the frozen version saves so much time.
  • ½ cup extra virgin olive oil

Directions (Note: Total baking time is 1 hour and 15 minutes.)

  • Cut the onions into chunks. For example, if you have medium-size onions, cut them into quarters and then again in half, so that you have eight chunks.
  • Place about 2 cups of the onion chunks into the work bowl of a food processor fitted with a metal blade. Using the pulse function, pulse for 4-6 times, or until you have small, but not tiny pieces of onion, as you can see here:
just some of the chopped onions
  • Empty the food processor and process the next two cups in the same manner; then repeat until all the onions have been chopped.
  • Take a rimmed baking sheet and line it with aluminum foil, parchment paper, or a silicone baking mat (for example, a Silpat mat that covers the entire pan, size 11 5/8 X16 ½-inch mat made for 13 X 18-inch sheet pan; US half size.) Place the lined baking sheet inside another rimmed baking sheet. (This creates an air pocket and keeps the onions from burning.)
  • Place the chopped onions on the lined baking sheet and drizzle half of the olive oil (¼ cup) over the onions. Mix the onions and olive oil to distribute the olive oil.
  • Using your hands (if you don’t mind them smelling like onions) or a non-metal spatula, spread the onions out evenly over the entire pan; set aside.
  • Take a third rimmed baking sheet and line it with aluminum foil or a silicone baking mat.
  • Pour 2 pounds (2, 1-pound bags) of frozen chopped spinach onto the lined baking pan.  Drizzle the remaining ¼ cup of olive oil over the spinach and mix the spinach around to distribute the olive oil.
  • Place the pan of spinach on the middle rung of the oven and the pan of onions on the lower rung of the oven.
onions and spinach going into the oven
  • Turn on the oven and set the temperature for 400 degrees F.  Note: In this case, I don’t preheat the oven, because it would just waste energy.
  • After 45 minutes, open the oven door —  WHILE TURNING YOUR FACE AWAY — so that you don’t get a blast of hot steam in your face. Take one pan out of the oven.
  • Use two spatulas and mix the more cooked veggies (those on the sides of the pan) with the less cooked veggies (those in the center of the pan). Then pat the veggies down so that they evenly cover the entire pan. Put the pan back into the oven on the rack it came from.
  • Remove the second pan of veggies from the oven. Use two spatulas and mix the more cooked veggies (those on the sides of the pan) with the less cooked veggies (those in the center of the pan). Then pat the veggies down so that they evenly cover the entire pan. Put the pan back into the oven on the rack it came from.
  • Let the pans of veggies bake for an additional 30 minutes.
  • Turn off the oven and remove both pans from the oven. Use the non-metal spatulas to mix the veggies in each pan around and then spread them out so that they can cool.
  • When cool, place the caramelized onions and roasted spinach in glass containers; refrigerate.
  • Of course, if you like, you can also freeze both the caramelized onions and the roasted spinach in – you guessed it – silicone mini muffin pans to make “flavor cubes” for use later. . (For more on the technique of freezing in silicone mini muffin pans, see Monamifood Basil Pesto Flavor Cubes.)

Enjoy and be healthy!



6 thoughts on “ONIONS & SPINACH: Caramelized Onions and Roasted Spinach

  1. The “crustless” quiches are fantastic!
    Perfect for brunch, lunch, or on a bed of spinach with tomatoes for a quick supper!
    Thanks, Leni!

    1. Hi Carole,
      Glad you like the crustless quiche recipe. It’s one of my all-time favorites, too. I plan to put that recipe on this blog very soon!

  2. Hi Leni,

    Thanks for posting about Dr. Servan-Schreiber and the Anticancer cause. I am the web developer & digital strategist for Dr. Servan-Schreiber and Anticancer. I just wanted to let you know that Dr. Servan-Schreiber will be posting his latest insight and research through his official Facebook page: http://www.Facebook.com/Anticancer and his new website: http://www.Anticancerbook.com

    Most recently, Dr. Servan-Schreiber and 40 renowned physicians & scientists presented new groundbreaking research regarding Vitamin D, while launching an international appeal and calling for new standard recommendations. http://www.anticancerbook.com/post/Vitamin-D-is-essential-for-the-prevention-of-cancer-heart-disease-osteoporosis.html

    Please let me know if you have any questions or need related Anticancer content.


    1. Hi Haysam,

      Thank you for your comment! I’m DELIGHTED that you found my blog! It was Dr. Servan-Schreiber’s book, Anti-Cancer, that inspired me to finally start my monamifood blog! I always turn to his book when I want to find a succinct summary of the research on food and cancer, and in almost every post on my blog you will find a reference to his book. I look forward to learning more from the new website, http://www.Anticancerbook.com — which looks great and will surely be my go-to source for the latest information on anti-cancer research that my readers and I can implement in our daily lives.


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