Smashburger-Inspired Double Cheeseburger with Caramelized Onions

By Lauren Mitchell, Test Kitchen Director · Reviewed by AislePrompt Editorial · Published 2026-06-20 · Updated 2026-06-20

A juicy double patty smashburger topped with melted cheddar and sweet caramelized onions, perfect for a flavorful American-style burger night. This american-inspired beef ready in about 40 minutes pairs ground beef (80/20), salt, black pepper for a weeknight-friendly dinner that comes together with one pan and minimal cleanup. Each serving lands at about 750 calories and feeds 2, so it slots cleanly into a weekly meal plan and pairs well with a quick salad or grain on the side. Tap "Plan a meal with the AI" below to drop this recipe into your week and send the ingredients straight to Instacart. Nutrition values are approximate, calculated from USDA FoodData Central (fdc.nal.usda.gov) — verify against ingredient labels for any health-driven dietary plan.

Ingredients

• 1 lb ground beef (80/20)
• 1 tsp salt
• 1/2 tsp black pepper
• 1 medium yellow onion
• 2 tbsp unsalted butter
• 4 slices cheddar cheese slices
• 2 burger buns
• 2 tbsp vegetable oil
• 2 tbsp mayonnaise
• 2 leaves lettuce leaves
• 4 slices tomato slices

Instructions

1. Step 1: Peel and thinly slice 1 medium yellow onion. In a skillet over medium-low heat, melt 2 tbsp unsalted butter and add sliced onions. Cook for 20 minutes, stirring occasionally, until onions are golden brown and caramelized with a sweet aroma.
2. Step 2: Divide 1 lb ground beef into 4 equal balls (about 4 oz each). Season each ball with 1/4 tsp salt and 1/8 tsp black pepper. Heat 2 tbsp vegetable oil in a cast iron skillet over high heat until shimmering.
3. Step 3: Place 2 beef balls in the skillet and smash each immediately with a spatula until about 1/2-inch thick. Cook for 2-3 minutes until edges are crispy and browned, then flip and cook 1 minute.
4. Step 4: Top each patty with 1 slice cheddar cheese and cook until melted, about 30 seconds. Remove patties and keep warm. Repeat with remaining 2 beef balls.
5. Step 5: Toast 2 burger buns in the same skillet for 1-2 minutes until golden.
6. Step 6: Assemble burgers by spreading 1 tbsp mayonnaise on each bun bottom, adding 1 lettuce leaf, 2 tomato slices, 2 cheesy patties, and a generous spoonful of caramelized onions. Cover with bun tops and serve immediately.