1. Prepare the French Onion Topping:
- In a large skillet, heat the butter and olive oil over medium heat.
- Add the thinly sliced onions and cook, stirring occasionally, until they start to caramelize and turn golden brown.
- Sprinkle sugar over the onions to aid in the caramelization process.
- Once the onions are nicely caramelized, pour in the beef broth to deglaze the pan. Cook for an additional 5 minutes, allowing the flavors to meld.
- Season with salt and black pepper to taste. Add fresh thyme leaves if desired. Set the French onion topping aside.
2. Prepare the Patties:
- Divide the ground beef into four equal portions. Form each portion into a patty and season with salt and black pepper.
- In the same skillet or a separate one, cook the beef patties over medium-high heat until they reach your preferred level of doneness.
3. Assemble the Patty Melts:
- Butter one side of each slice of rye bread.
- Place a slice of Swiss cheese on the unbuttered side of four slices of bread.
- Top the cheese with a cooked beef patty.
- Spoon a generous amount of the French onion topping over the patty.
- Place a second slice of Swiss cheese on top of the onions.
- Complete the sandwich with another slice of rye bread, buttered side facing out.
4. Grill the Patty Melts:
- In a clean skillet over medium heat, grill each sandwich until the bread is toasted and the cheese is melted, flipping halfway through.
- Press the sandwiches down with a spatula while grilling to ensure they are evenly cooked and the cheese is melted.
5. Serve:
- Once the patty melts are golden brown and the cheese is gooey, remove them from the skillet.
- Slice diagonally and serve hot.
Enjoy your French Onion Patty Melt with its savory French onion topping, juicy beef patty, and gooey Swiss cheese! It’s a flavorful twist on the classic patty melt.