Prep ingredients: Preheat oven to 450°F with a rack in the upper third. Peel 3 large garlic cloves; finely chop 2, leave 1 whole. Finely grate parmesan. Thinly slice mozzarella. Trim ends from broccolini, then cut lengthwise, if large. On a rimmed baking sheet, toss broccolini with 2 tablespoons oil; season with salt and pepper. Arrange on half of the baking sheet.
Make meatballs: in a medium bowl, whisk together 1 large egg and 1⁄4 cup of the panko (save rest for own use). Add pork, 1⁄2 of each the chopped garlic and parmesan, 1 teaspoon of the Italian seasoning (save rest for own use), 1⁄2 teaspoon salt, and a few grinds pepper. Stir to combine. Shape into 8 meatballs; place on opposite side of baking sheet.
Roast ingredients: roast meatballs and broccolini in the upper third of oven until meatballs are cooked through and broccolini is crisp-tender, 10-12 minutes.
Make sauce: while meatballs and broccolini roast, heat 1 tablespoon oil and remaining chopped garlic in a medium ovenproof skillet over medium-high until sizzling, about 1 minute. Add 1⁄3 level cup tomato paste and cook, stirring, about 2 minutes. Add 1 1⁄4 cups water, 1⁄2 teaspoon each salt and sugar, and a few grinds pepper. Simmer until reduced to 3⁄4 cup, about 5 minutes.
Broil meatballs: switch oven to broil. Add meatballs to skillet with sauce, spooning some sauce over tops of meatballs. Top with mozzarella and remaining parmesan. Place skillet on top oven rack and broil until mozzarella is melted, 2-3 minutes (watch closely). Place broccolini on lower oven rack to rewarm, if necessary.
Make garlic bread & serve: slice ciabatta in half, horizontally, if necessary. Generously brush cut-sides with oil, and season with salt and pepper. Place directly on top oven rack and broil until lightly toasted, 2-3 minutes. Rub cut-sides of ciabatta with whole garlic clove, then cut into 1-inch slices. Serve meatball skillet alongside garlic bread "soldiers" and broccolini. Enjoy!