Two-Cheese Bacon Burger with Creamy Caramelized Onion Sauce

4 servings

An umami-rich gourmet burger on a Euro-Bake brioche to hold all that flavor!

4 servings

An umami-rich gourmet burger on a Euro-Bake brioche to hold all that flavor!

1 tbsp. olive oil, plus more for drizzling
3 tbsp. butter, at room temperature
2 large or 3 medium onions, quartered and thinly sliced
Salt and finely ground black pepper
1/2 cup beef consommé or beef stock
1 cup sour cream
8 slices meaty bacon
1 1/2–2 lbs. 80% lean ground beef
Kosher salt and coarsely ground black pepper
2 tbsp. Worcestershire sauce
4 slices Swiss cheese
4 slices white American cheese
4 brioche or potato burger rolls, split
2 tbsp. Dijon mustard
Pickle relish or sliced sandwich-size pickles
Leaf lettuce or little gem leaves