Name: French Onion Patty Melt with Caramelized Onions
Prep time: 20 min
Cook time: 45 min
Total time: 1 h 5 min
Cuisine: American Comfort Food
Ingredients: 2 lbs ground beef 80/20; 12-14 slices Swiss cheese; 1.5 cups Gruyere cheese, shredded; 2 large yellow onions, thinly sliced; 6-8 slices thick cut bread; 2.5 tbsp kosher salt; 2.5 tbsp black pepper; 2 tbsp garlic powder; 2 tbsp brown sugar; 2 tbsp mayonnaise; 2 tbsp ketchup; 2 tbsp yellow mustard; 1 tbsp pickled relish; 1.5 tsp hot sauce

Description

This French Onion Patty Melt elevates the classic diner sandwich with rich caramelized onions, double layers of melty Swiss and Gruyere cheese, and crispy-edged beef patties—all sandwiched between golden toasted bread with a tangy homemade diner sauce.

Ingredients

Scale

2 lbs ground beef 80/20
12–14 slices Swiss cheese
1.5 cups Gruyere cheese, shredded
2 large yellow onions, thinly sliced
6–8 slices thick cut bread
2.5 tbsp kosher salt
2.5 tbsp black pepper
2 tbsp garlic powder
2 tbsp brown sugar
2 tbsp mayonnaise
2 tbsp ketchup
2 tbsp yellow mustard
1 tbsp pickled relish
1.5 tsp hot sauce

Instructions

Form 2.5-3 oz beef balls and refrigerate for 30 minutes. Mix all diner sauce ingredients and refrigerate until ready.
Preheat grill to 350°F. Add cast iron skillet 2 minutes before cooking.
Add beef balls to hot skillet. Cover with parchment paper and smash firmly with spatula. Cook 1-2 minutes, flip, and season cooked side.
Add sliced onions to skillet. Cook 30-45 minutes until dark brown. Add seasonings and brown sugar halfway through.
Layer sandwich: bread with sauce, onions, Gruyere, patty, Swiss, patty, Swiss, onions, Gruyere, bread with sauce.
Cook assembled sandwiches on clean skillet 1-2 minutes per side until golden. Cool briefly and serve with fries and pickles.

Notes

Chill beef balls before cooking to maintain shape and prevent overcooking during the smashing process
Use parchment paper when smashing to prevent sticking and ensure even pressure distribution
Don’t rush the onion caramelization – low and slow cooking develops the best flavor and color
Layer cheese strategically to create maximum melting and flavor integration throughout the sandwich
Toast assembled sandwiches on medium heat to ensure cheese melts completely before bread burns

Prep Time: 20 minutes
Cook Time: 45 minutes
Category: Sandwich
Method: Grilled
Cuisine: American Comfort Food

Nutrition

Serving Size: 1 sandwich
Calories: 850
Sugar: 12g
Sodium: 1250mg
Fat: 52g
Saturated Fat: 24g
Unsaturated Fat: 26g
Trans Fat: 2g
Carbohydrates: 48g
Fiber: 3g
Protein: 45g
Cholesterol: 165mg

Keywords: patty melt, french onion sandwich, diner burger, smash burger sandwich, grilled sandwich, beef patty melt