Step 1

Heat a medium skillet over medium heat

Step 2

Add 2 tablespoons butter and melt

Step 3

Add onions and season with salt and white pepper

Step 4

Add the sugar and cook, stirring frequently, until very soft and light caramel in color, 20 to 25 minutes

Step 5

Add bone broth or consomme and reduce heat to warm/low

Step 6

Meanwhile, heat olive oil, 2 turns of the pan, in a medium nonstick skillet over medium-high heat

Step 7

Melt 2 tablespoons butter into the oil, then add mushrooms and brown

Step 8

Season with salt and pepper, add thyme and garlic and stir a minute, then add wine or sherry and reduce heat to warm/low

Step 9

Listicle: Rachael Ray 12-Inch Cast Iron Frying Pan Meanwhile, heat a cast-iron skillet over medium-high heat

Step 10

Place meat in bowl and season with Worcestershire, salt and pepper, then form 4 patties thinner at the center for even cooking

Step 11

Spray the pan with oil and cook the patties for 4 minutes, then flip, baste liberally with steak sauce and cook 4 minutes more

Step 12

Top the burgers with 2 slices cheese each and build burgers: bun bottom, Dijon, mushrooms, patties, onions, bun top