The Best Hamburgers Ever

I got these from Ina Garten on FoodNetwork. They are so good cooked on the grill, but could also be broiled. BEWARE: these have plenty of fat--not for the faint of heart!LOL

• Ready In: 20 mins
• Serves: 12

Ingredients

• 2  lbs  ground chuck
• 1  lb  ground sirloin
• 3  tablespoons  steak sauce (I use A1)
• 6  extra-large egg yolks
• 1 1⁄2 teaspoons kosher salt
• 3⁄4 teaspoon ground black pepper
• 4  tablespoons  cold butter
• 12  hamburger buns

Directions

1. Mix meats, steak sauce, egg yolks, salt and pepper with fork (do not over-work).
2. Form mixture into 12 balls.
3. Put a thin slice of butter in the middle of each ball, then flatten into patties (make sure butter is completely surrounded by meat).
4. Cook for 3-5 minutes per side until done.
5. Remove to plate, cover with foil, and allow to rest for 5 minutes before serving.