ingredients
1 lb ground beef
1 yellow onion
3 slices cheese
3 brioche buns
2 tbsp butter
2 tbsp oil
8 oz bacon

sauce
1/4 cup mayo
2 Tbsp ketchup
1 Tbsp mustard
1 Tbsp sweet relish
1/4 tsp each salt and pepper

Add your bacon to a sheet pan. Bake at 400f for about 15-18 minutes.

In a frying pan over medium heat, add oil and sliced onions. Season with salt and a small pinch of sugar. Cook stirring often for 15-20 minutes until nicely caramelized.

In a small bowl, mix all sauce ingredients. Set aside.

Shape your beef into three even patties (I used deli container lids). Season your patties with salt and pepper on both sides. Heat a cast iron over medium high heat for 3 minutes. Add 2 Tbsp oil and add two of your patties. Cook for 3 minutes, then flip and cook for 2 more minutes. Then add cheese and cook until melted.

To assemble, on toasted buns add sauce, a patty, caramelized onions and bacon.
Top your burger and enjoy!

source