Description

This melty grilled cheese sandwich features smoky bacon, sweet caramelized onions, and a blend of sharp cheddar and creamy Fontina, all tucked between crispy, golden sourdough slices. It’s the ultimate comfort food, perfect for lunch, dinner, or a decadent snack.

Ingredients

Scale

2 slices sourdough bread (or brioche, sandwich bread, or gluten-free bread)
2 thick-cut bacon slices
1/2 large yellow onion, thinly sliced
1 tablespoon unsalted butter (plus more for brushing, optional)
1 tablespoon mayonnaise
1/4 cup (30g) sharp cheddar cheese, grated
1/4 cup (30g) Fontina cheese, grated (or Gruyère, Swiss, Gouda, or mozzarella)
Salt and pepper, to taste
Optional: 1/2 teaspoon fresh thyme, chopped

Instructions

Caramelize the onions: Heat 1 tablespoon butter in a skillet over medium-low. Add thinly sliced onions and a pinch of salt. Stir every few minutes until golden brown, soft, and jammy, about 12-15 minutes. If onions start to stick, add a splash of water. Remove and set aside.
Cook the bacon: In the same pan, cook bacon slices over medium heat until crispy, flipping halfway, about 5-7 minutes. Drain on paper towels.
Prep the cheese: Grate cheddar and Fontina cheese and mix together in a small bowl.
Prepare the bread: Spread butter on one side of each bread slice and mayonnaise on the other. The butter side will touch the pan, mayo side faces out.
Assemble the sandwich: On one slice (butter side down), layer half the cheese, all the caramelized onions, bacon, and the rest of the cheese. Top with the second slice (butter side up).
Grill the sandwich: Heat skillet over medium. Place assembled sandwich in the pan and press gently with a spatula. Cook for 2-3 minutes until golden brown. Flip, press again, and cook another 2 minutes. If cheese isn’t fully melted, cover the pan for 1 minute.
Rest & slice: Remove from pan, let sit for 1 minute, then slice in half and serve.

Notes

For extra crispiness, use a bacon press or heavy pan. Mayo on the outside of the bread creates a golden, crunchy crust. Let the sandwich rest for a minute before slicing to prevent cheese from oozing. Customize with different cheeses, herbs, or add-ins like jalapeños or apples. Gluten-free and vegan versions are possible with substitutions.

Prep Time: 15 minutes
Cook Time: 10 minutes
Category: Main Course
Cuisine: American

Nutrition

Serving Size: 1 sandwich
Calories: 480
Sugar: 6
Sodium: 950
Fat: 28
Saturated Fat: 13
Carbohydrates: 36
Fiber: 3
Protein: 20

Keywords: grilled cheese, bacon, caramelized onion, sandwich, comfort food, melty cheese, easy lunch, sourdough, cheddar, Fontina