Mushroom Swiss Smash Burgers with Truffle Sauce

Ingredients

• 0.5 cups mayonnaise
• 2 teaspoons fresh lemon juice
• 0.75 teaspoons truffle oil
• 1 teaspoon finely chopped fresh parsley
• 1 clove garlic , grated
• 1.25 teaspoons salt , divided
• 0.13 teaspoons plus 1/2 tsp. black pepper
• 3 tablespoons unsalted butter
• 1 package sliced cremini mushrooms , 16 ounce
• 5 sprigs thyme
• 1 teaspoon Worcestershire sauce
• 0.25 teaspoons garlic powder
• 0.25 teaspoons onion powder
• 0.25 teaspoons paprika
• 1.25 pounds ground chuck
• 4 slices Swiss cheese
• 4 kaisers rolls , split and toasted

Instructions

1. 1

   Whisk together mayonnaise, lemon juice, truffle oil, parsley, garlic, 1/4 teaspoon salt, and 1/8 teaspoon pepper in a small bowl.

2. 2

   Melt butter in a large cast-iron skillet over medium-high heat. Stir in mushrooms and thyme sprigs; cook, stirring occasionally, until mushrooms are tender and golden brown, about 10 minutes. Discard thyme sprigs. Season with 1/2 teaspoon salt and Worcestershire sauce. Transfer mushroom mixture to a bowl; keep warm for serving. Wipe out skillet.

3. 3

   Stir together garlic powder, onion powder, paprika, and remaining 1/2 teaspoon each salt and pepper for the rub. Divide beef into 4 portions; gently shape into balls.

4. 4

   Heat same skillet over medium-high heat. Working in batches as needed, add meat portions to dry skillet; press down firmly with a flat spatula or grill press into 41/2-inch-diameter patties. Sprinkle evenly with rub. Cook 2 minutes per side or until well browned. Top patties with Swiss cheese and cook about 30 seconds until cheese is melted and an instant- read thermometer inserted into centers registers at least 160 degrees F (71 degrees C).

5. 5

   To assemble burgers, spread bun tops and bottoms with truffle mayo. Fill buns with patties and sautéed mushrooms.