Roasted Butternut Squash and Balsamic Onion Melt

When I want a lunch that feels a bit more special than a standard grilled cheese, I reach for this butternut squash and balsamic onion melt.

The sweetness of the roasted squash pairs perfectly with the tangy balsamic onions, and the Havarti cheese keeps everything held together with a nice, creamy finish.

It is a great way to use up leftover squash, and because you roast the vegetables first, you get a much deeper flavor than if you just pan-fried them. It is a hearty, comforting meal that comes together in about 40 minutes.

Key Ingredients & Notes

• Butternut Squash: Make sure to cut your cubes into small, half-inch pieces. If they are too large, they will be difficult to bite through once they are inside the sandwich.
• Balsamic Vinegar: Use a standard balsamic vinegar here. You want to cook it down until the pan is dry so the onions are sticky and sweet, not soggy.
• Havarti Cheese: This is my go-to for this sandwich because it melts beautifully. If you cannot find Havarti, a mild fontina or even a good white cheddar works well too.
• Sourdough Bread: A sturdy sourdough holds up best to the weight of the roasted squash without getting too soft.

Roasted Butternut Squash and Balsamic Onion Melt Recipe

Roasted Squash and Balsamic Onion Melt

This vegetarian sandwich features tender roasted butternut squash and sweet balsamic glazed onions melted between crispy sourdough bread.

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Prep Time 10 minutes mins

Cook Time 30 minutes mins

Total Time 40 minutes mins

Course Breakfast

Cuisine American

Servings 1

Ingredients

  

• Roasted Squash and Onions
• 1 cup butternut squash cut into half-inch cubes
• 1 tablespoon olive oil
• 1 cup red onion thinly sliced
• 1 tablespoon balsamic vinegar
• 0.25 teaspoon dried thyme
• Salt and black pepper to taste
• Sandwich Assembly
• 2 slices sourdough bread
• 2 slices Havarti cheese
• 1 tablespoon butter softened

Instructions

 

• Preheat your oven to 400 degrees F and line a small baking sheet with parchment paper.
• Toss the squash cubes with half the olive oil and a pinch of salt and pepper on the baking sheet.
• Roast the squash for 15 to 20 minutes until tender and lightly browned.
• While the squash roasts, heat the remaining olive oil in a small skillet over medium heat.
• Add the sliced onions to the pan and cook until soft and golden brown.
• Pour the balsamic vinegar and dried thyme into the skillet and stir until the vinegar coats the onions and no liquid remains in the pan.
• Butter one side of each bread slice.
• Place one slice of bread butter-side down in a clean skillet over medium-low heat.
• Layer one slice of cheese, the roasted squash, the balsamic onions, and the second slice of cheese onto the bread.
• Top with the remaining bread slice, butter-side up.
• Cook until the bottom bread is toasted, then flip and cook until the second side is toasted and the cheese is melted.

Keyword Roasted Squash and Balsamic Onion Melt

Tima’s Tips

• Using cubed squash instead of slices makes the sandwich easier to eat and keeps the filling contained.
• Keep your heat at medium-low while grilling the sandwich so the bread toasts evenly before the cheese burns.

Variations to Try

• Add a handful of fresh baby arugula to the sandwich right before serving for a peppery crunch.
• Sprinkle a little bit of goat cheese on top of the squash for an extra tangy bite.
• Add a thin layer of fig jam to the inside of the bread if you like a sweeter profile.

Storage

This sandwich is best eaten right away while the bread is crispy and the cheese is warm. If you have leftover roasted squash and onions, store them in an airtight container in the fridge for up to 3 days and assemble the sandwich fresh when you are ready to eat.

Common Questions I Get

If you make this, let me know how it turned out in the comments below — I'd love to hear from you.