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How to Cook Costco French Onion Soup [+ Side Dish Ideas]

How To Cook Costco French Onion Soup
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Costco French onion soup is the only soup I’ve cooked in the oven instead of on the stovetop because it is a soup you bake. Delicious, rich, and refined, this rustic Costco dish continuously amazes me with its special flavor notes that tickle my curiosity. Still, this dish may not get a chance to surprise you if you don’t know how to cook it. So, how to cook Costco French onion soup?

In a nutshell, cooking Costco French onion soup consists of preheating the oven and baking the soup. The process has certain particularities you should know to get the best possible results.

Costco French onion soup is one of my favorite comfort foods, midday snacks, or side dishes. Depending on my mood, it always gives me what I need. In this article, I will explain everything you need to know about cooking Costco French onion soup so that you can enjoy it with all your senses.

Costco French Onion Soup Recipe

Costco French Onion Soup Cooking Instructions 

Preparing Costco French onion soup is simple, but knowing some extra stuff will significantly enhance your experience. So, below, I’ve compiled a few steps that will undoubtedly make your job easier and your soup tastier. 

Preparation

In my opinion, the first step is the most important one and, sadly, the one most people overlook. So, to begin the process of cooking your delicious Costco French onion soup, you first must preheat the oven. You get the soup fully frozen, and cooking it on a stovetop won’t do. 

If you don’t preheat the oven and pop the soup while the oven is still hot, you risk getting a mushy and gooey meal that, believe me, you won’t like. So, start by preheating your oven to 400 °F (200 °C). After removing the soup from its packaging, place it in an oven-safe crockpot and pop it in the oven once it has preheated, which is about ten minutes after you’ve turned it on.

If you want to preheat more than one, I strongly recommend that you use individual crockpots for each one. If you place all soups into one large crockpot, they may not turn as well as you think. 

Grating Cheese for French Onion Soup

If you want your soup cheesier, now would be a good time to sprinkle some grated cheese on top. I like to cover it with a thick layer of mozzarella and pop it into the oven. 

Time to Bake! 

This is the step where you don’t have to do anything other than popping the soup into the oven, but you do have to be alert, especially if this is your first such experience. I like to use parchment paper and place the soup crockpot onto a parchment paper-covered baking tray. 

If you don’t want to do this, just put the soup on the oven rack, but never place it on the bottom plate because it will definitely ruin your soup. 

So, once your Costco French onion soup is inside the oven, lower the temperature a little to make sure that it will gradually cook through equally. I usually bake it at 360 °F, i.e., 180 °C. 

It usually takes about 15-20 minutes for the soup to cook thoroughly, but I advise you to observe it after ten minutes because the cooking time is highly dependent on the oven power. So, it’s safer to check if it seems ready before the 15-20 minute mark. 

Always place the crockpot on a dry and thick coaster, and make sure your oven mints aren’t wet when you hold the crockpot. Never place the crockpot on the stovetop without a coaster or at least a folded dry cotton kitchen towel.

Optional but Preferred Step

Crank the flavors up with this special step! If you are anything like me, you must try your Costco French onion soup with an extra crispy and caramelized cheese topping. To achieve this effect, switch the oven to broil mode and broil the soup for the last one to two minutes. So instead of baking the soup for 15-20 minutes, bake it for 13-18 minutes and then switch to broil. 

Once the cheese gets golden and bubbly, it means that it’s time to remove the soup from the oven. Be warned that it takes very little time, a few seconds probably, for the cheese to move from golden and bubbly to burnt, so act quickly. 

Let Your Soup Set 

This final step is just as important as the rest of the steps, so please don’t skip it. Once your Costco French onion soup is cooked, don’t serve it immediately, and give it time to set. Place it on the counter and let it rest for about 15 minutes before transferring it to a bowl. 

This way, the flavors will set together, creating a wonderful union allowing you to experience each tasting note. 

How to Make Costco French Onion Soup Better?

To further enhance your Costco French onion soup, try adding some fresh herbs after you cook it. Even though herbs are usually added while cooking, Costco French onion soup seems to not have a problem if you add the herbs later. 

I like to sprinkle chopped fresh thyme or parsley on top of the soup just before serving. It gives the soup a delightful crunch, adds freshness, and makes it more colorful and appetizing.

After you cook the soup, you can add some beef broth to the pot. Make the broth beforehand and add just a few spoons to the crockpot. It will give it an even more savory note. 

Add a splash of red wine to your Costco French onion soup for more depth of flavor. It will pierce through the savory notes with its acidity, balancing everything out. Just a few drops of a soft red wine such as Merlot or Cabernet Sauvignon will do just fine. 

What to Serve with Costco French Onion Soup?

French Onion Soup With Toasted Baguette

Costco French onion soup matches great with a vast sea of sides. To simplify things, you can always pair it with what you usually have, French onion soup, but if you lack ideas, I got you covered. 

You can never go wrong with the old classics such as a baguette, focaccia bread, croutons, bruschetta, or any type of crusty bread you may like or have at home. 

Salad is also one of those sides that always wins the dish. From the good old green salad to a fancier and creamier delicacy, you can pair your Costco French onion soup with any veggies you have at home. So, go wild and make yourself whatever salad you like best. 

If you have any Brussels sprouts or starchy veggies just lying around, there is no better way to use them than pairing them with your Costco French onion soup. Pop them in the oven, drizzle with oil, sprinkle some salt and pepper, and enjoy your roasted veggies and creamy soup. 

Costco French onion soup is also a great way to use up your meat leftovers, as it pairs heavenly with any type of meat. So, whether you have leftover chicken, turkey, pork, or beef, whip them out and enjoy your feast.

Costco French Onion Soup Cooking Instructions

Costco French Onion Soup from the Oven

Author: Laura Bais
Here are the cooking instructions for a bowl of delicious Costco French onion soup. Enjoy!
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Prep Time 5 minutes
Cook Time 15 minutes
Total Time 20 minutes
Course Main Course
Cuisine American
Servings 1 serving
Calories 210 kcal

Equipment

  • Baking tray
  • Parchment paper

Ingredients
  

  • 1 Costco French Onion Soup

Instructions
 

  • Preheat the oven to 400 °F (200 °C).
  • Take one soup out of the pack and put it into an oven-safe crockpot.
  • Use parchment paper and place the soup crockpot onto a parchment paper-covered baking tray. Pop the tray into the oven.
  • Once your Costco French onion soup is inside the oven, lower the temperature to 360 °F, i.e., 180 °C.
  • After 13 mins, switch the oven to broil and broil for 2 more minutes or until your soup is done.
  • Once the cheese gets golden and bubbly, it means that it's time to remove the soup from the oven.
  • Place it on the counter and let it rest for about 15 minutes before transferring it to a bowl. Once the flavors have set, enjoy your Costco French onion soup with a fresh salad!

Nutrition

Serving: 1servingCalories: 210kcalCarbohydrates: 15gProtein: 13gFat: 10gSaturated Fat: 7gCholesterol: 35mgSodium: 740mgPotassium: 176mgFiber: 3gSugar: 4gCalcium: 268mg
Keyword Costco French Onion Soup, Costco French Onion Soup Cooking Instructions, How to Cook Costco French Onion Soup

Before diving into the nutritional details, please review our Nutritional Disclaimer page for important context and clarifications.