Caramelize the onions: Heat the oven to 400 degrees (if you have a toaster you can skip this step!). Halve, peel, and thinly slice the onions. Heat a drizzle of oil in a large pan over medium heat. Add the onion and 1 teaspoon sugar to the pan and cook, tossing, for 6-8 minutes, until caramelized. Season with salt and pepper, then set aside.

Make the vinaigrette: mince or grate the garlic. In a large bowl, whisk together 1 tablespoon tomato paste, 2 tablespoons balsamic, 2 tablespoons olive oil, and garlic (to taste—start with a little and go up from there!). Season with salt and pepper.

Cook the burgers: Form the ground beef into 2 patties. In the same pan you cooked the onions in, heat anther drizzle of oil over medium-high heat. Season the patties on all sides with salt and pepper, then place in the pan and cook for 2-4 minutes per side, or until almost cooked to desired doneness. Top the patties with the mozzarella and Parmesan cheese, then cover and cook another 1 minute, until the cheese melts.

Toast the bread: While the patties cook, halve the ciabatta rolls and place in the oven or toaster to toast for 3-5 minutes.

Dress the salad: Toss the arugula into the vinaigrette and season with salt and pepper.

Assemble the burgers: place each patty inside a bun, then top with the caramelized onion and a bit of the tossed arugula. Serve the remaining arugula salad to the side and enjoy!