Thick sliced bread topped with soft onions, sautéed mushrooms, and havarti cheese is the perfect grilled cheese combination! This caramelized onion and mushroom grilled cheese is a great easy meal!
Grilled cheese is basically my love language, and a good grilled cheese cannot be beat! Making this sandwich comes together quickly and is the perfect lunch or dinner! Pair this Caramelized Onion and Mushroom Grilled Cheese with a Simple Wedge Salad or French Fries for the perfect quick meal!
How to make this Caramelized Onion and Mushroom Grilled Cheese:
**scroll down for full ingredients list and printable directions**
- Caramelize the onions & mushrooms: Heat skillet on medium heat and melt the butter. Add onions and mushrooms to skillet. After about 5-7 minutes you will notice the mushrooms ‘sweating’, little beads of water coming to the surface. Wait another minute and then toss around quickly, and leave them again. Wait about 5 more minutes. By this time their color should be turning a rich brown, and you can toss around a couple more times. Once they are a caramel color, they are done.
- Sprinkle thyme and salt and pepper over mixture and stir.
- Assemble the sandwich: Butter one side of each bread slice. Then, with the butter side facing down, add 1 slice of cheese, ½ cup of the mushroom mixture, and another slice of cheese. Add the other slice of brad with the butter facing out. Repeat for 2nd sandwich.
- Cook the sandwiches: Place the sandwiches into a skillet on medium heat (lower the heat if your bread is browning, but cheese isn't melting enough). and cook for 3-4 minutes and then flip carefully to other side. Cook an additional 3-4 minutes or until browned.
- Remove from skillet, cut in half, and serve!
Serve the sandwiches with a delicious side dish such as:
- The Crispiest and Best Air Fryer Baked Potatoes
- Air Fryer French Fries (homemade)
- In-N-Out Animal Style Fries (Copycat)
- Honey Lime Fruit Salad
- Air Fryer Asparagus Fries (easy recipe)
If you like grilled cheese as much as I do, be sure to check out these other sandwiches from Domestic Superhero:
- Spinach Pesto Grilled Cheese
- California Grilled Cheese (Turkey, Avocado, Tomato)
- Turkey Cranberry Grilled Cheese (Thanksgiving Leftover Sandwiches)
- Apple Grilled Cheese
- Roasted Red Pepper Grilled Cheese
- BBQ Chicken & Pineapple Grilled Cheese
- Caprese Grilled Cheese
Thick sliced bread topped with soft onions, sautéed mushrooms, and havarti cheese is the perfect grilled cheese combination! This caramelized onion and mushroom grilled cheese is a great easy meal!
- 8 oz mushrooms roughly chopped
- 1 medium onion thinly sliced
- salt & pepper
- ½ teaspoon thyme dried or fresh
- 4 slices of thick sliced bread (like sourdough)
- 4 slices havarti or Swiss cheese
- 2 TBS butter
-
Heat skillet on medium heat and melt 1 TBS of butter; Add onions and mushrooms. After 5-7 minutes you'll notice the mushrooms ‘sweating’ (little beads of water coming to the surface) - Wait another minute and then toss around quickly; Wait about 5 more minutes. By this time their color should be turning a rich brown, and you can toss around a couple more times. Once they are a caramel color, sprinkle with thyme, salt and pepper and stir. Remove from heat.
-
Using the remaining butter, evenly butter 1 side of each slice of bread. With the butter side facing down, place 1 slice of cheese on bread, then about ½ cup of mushroom mixture, then another slice of cheese, and then another slice of bread with the butter side up. Repeat for 2nd sandwich.
-
Place the sandwiches into a skillet on medium heat (lower the heat if your bread is browning, but cheese isn't melting enough). Let cook for 3-4 minutes and then flip carefully to other side. Cook an additional 3-4 minutes or until browned.
-
Remove from skillet, cut in half, and serve immediately.
*Do not cook sandwiches over high heat, this will toast the bread to quickly and not allow enough time for the cheese to melt. Slowly over medium head is the way to go.
Recipe first published in 2013. Updated 2/2025
Kim says
Yum! This looks so delicious! 🙂
Allyson says
Thanks so much, Kim!
jessica says
i dont like mushrooms. what do you suggest in their place?
Allyson says
Maybe some steak? I don't really know what else would go well with caramelized onions, but I am pretty sure steak would be a good option!
kelley @ Miss Information says
OMG this looks so good when are we getting together for lunch!
Allyson says
Haha, thanks Kelley! You can come over anytime 😉
Tristian says
I'm making this tonight since I bought a block of havarti at your suggestion. Can't wait to try it.
Allyson says
Yum! Let me know how it turns out!!!
Tristian MacKinnon says
omg, it was so good! I think I might try some sauteed spinach next time to add more veggies to it. Justin asked me to make him another and Afton just had a havarti grilled cheesed. I was the best mom ever even for just a few minutes.
Allyson says
Yay! I am so happy y'all loved it! When I first made this recipe I was actually going to add spinach because I had some on hand, but I didn't want it to be too much! I Would DEFINITELY give it a try, and let me know how it is!
nicole (thespicetrain.com) says
Oh, wow, I've got to try these, what a great idea!
jocieopc says
Happy Thanksgiving!! Just wanted to let you know this will be featured tonight on the blog - thanks so much for linking up!
Mushrooms Canada says
I go through spurts where all I crave is a good sandwich and this would be the perfect solution! Thanks for sharing...
-Shannon
Christine (CookTheStory) says
Cheese and bread work for me too. Yummy.
Heather says
A delicious combination! Great directions for preparing the mushrooms.
Allyson says
So happy you enjoyed them!