The Molly's Burger Recipe

Heat a large skillet over medium-low heat. Add olive oil and butter until melted. Add the thinly sliced onion and sprinkle with sugar and salt. Cook, stirring occasionally, until deep golden brown and soft, about 25–30 minutes. If onions begin to stick or dry, add a splash of water. In the last 1–2 minutes, stir in balsamic vinegar if using. Remove from heat and keep warm.

Preheat oven to 400°F (200°C). Arrange bacon slices on a wire rack set over a rimmed sheet pan. Bake 12–18 minutes, depending on thickness, until crisp. Transfer to paper towels to drain and keep warm. Alternatively, fry in a skillet over medium heat, turning, until crisp; drain on paper towels.

In a small bowl or a mini food processor, combine mayonnaise, lemon juice, grated garlic, salt, and pepper. Add cold heavy cream. Whip vigorously by hand or pulse in the processor until mixture is slightly aerated and spreadable (about 30–45 seconds). Taste and adjust seasoning. Refrigerate until assembly.

Make the horseradish cheddar by stirring prepared horseradish into the sliced cheddar. If the horseradish is very stiff, add the teaspoon of milk and mix until the horseradish disperses into the cheese slices, making them zesty but not overpowering. Reserve sliced cheese until patty finishing.

Form and Season

Divide ground chuck into two equal portions (about 8 oz each). Gently form into loose patties slightly larger than buns, about 3/4" thick, with a shallow dimple in the center. Season both sides with kosher salt and freshly ground black pepper just before cooking.

Cook Patties

Heat a cast-iron or heavy skillet over medium-high heat. Add vegetable oil and swirl to coat. When shimmering, add the patties, dimple-side up. Cook without moving 3–4 minutes until a brown crust forms. Flip and cook another 3 minutes for medium-rare to medium. During the last 1–1.5 minutes, place the horseradish cheddar slices on top of each patty and cover the pan for 1 minute to melt the cheese slightly. Remove patties and rest 2–3 minutes on a warm plate.

Toast buns: Spread softened butter on cut sides of buns. In a clean skillet over medium heat or on a griddle, toast buttered cut sides until golden, about 1–2 minutes. Assemble each burger as follows: Spread a generous tablespoon of whipped mayo on each bun bottom. Top with 2 lettuce leaves, then place the cheese-topped patty. Add 2 slices of crispy bacon across the patty, a generous spoonful of caramelized onions, and 2–3 tomato slices. Season tomato with a light pinch of salt and a grind of pepper. Spread more whipped mayo on the top bun and close burger. Serve immediately.