Step 1: Make the Spicy Sauce

1. In a small bowl, mix together mayo, ketchup, mustard, hot sauce, smoked paprika, and garlic powder.

2. Taste and adjust heat level.

3. Cover and chill until ready to use.

Step 2: Caramelize the Jalapeño-Onion Mix

1. Heat 1 tbsp oil or butter in a skillet over medium heat.

2. Add sliced onions and cook for 5 minutes until softened.

3. Add jalapeños, sugar, and a pinch of salt.

4. Cook another 5-6 minutes, stirring occasionally, until deeply golden and tender.

5. Remove from heat and set aside.

Step 3: Form and Season the Patties

1. Divide ground beef into 4 equal balls (don’t overwork the meat).

2. Season each ball with salt, pepper, garlic powder, and smoked paprika.

3. Keep chilled until ready to cook.

Step 4: Smash & Sear the Burgers

1. Heat a cast iron skillet or griddle over medium-high until very hot.

2. Add oil or butter, then place 2 beef balls on the surface.

3. Immediately smash each ball flat with a spatula (use parchment paper and a second spatula if needed).

4. Sear for 2-3 minutes until the edges are crispy and brown.

5. Flip, then top each patty with cheese.

6. Cover with foil or lid and cook 1 more minute to melt the cheese.

7. Repeat with remaining patties.

Step 5: Toast the Buns

1. While burgers cook, lightly toast the buns in a dry skillet or under the broiler for 1-2 minutes.

Step 6: Assemble the Burgers

1. Spread spicy sauce on both sides of the bun.

2. Add lettuce or cabbage to the bottom bun.

3. Place the cheesy smash burger patty on top.

4. Spoon over a generous amount of jalapeño-onion mix.

5. Add tomato slices or pickles if using.

6. Top with the other bun half and press gently.