Preheat oven to 425 degrees. Wash and dry all produce. Cut potatoes into 1/2-inch-thick wedges. Mince or grate garlic. Halve buns. In a small bowl, combine mayonnaise and a small pinch of garlic (you’ll use more later).

In a medium bowl, combine beef, panko, half the Tuscan Heat Spice, and 3/4 tsp salt (11/2 tsp for 4 servings). Form into 10-12 11/2-inch meatballs (20-24 for 4).

Toss potatoes on a baking sheet with a large drizzle of olive oil, salt, and pepper. Roast on top rack for 20 minutes (you’ll add more to the sheet then).

Meanwhile, heat a drizzle of olive oil in a large, preferably nonstick, pan over medium-high heat. Add meatballs; cook, turning occasionally, until browned and cooked through, 8-10 minutes. Transfer to a plate; discard fat from pan. Add a drizzle of olive oil to same pan over medium heat. Stir in crushed tomatoes, 1/4 cup water (1/3 cup for 4), 1/2 tsp salt (1 tsp for 4), 1/2 tsp sugar (1 tsp for 4), and remaining garlic and Tuscan Heat Spice. Simmer until thickened, 5-7 minutes. Turn off heat; stir in 1 TBSP butter (2 TBSP for 4).

Slice meatballs in half and gently stir into sauce. Once potatoes have roasted 20 minutes, remove baking sheet from oven and push potatoes to one side. Place buns cut sides up on empty side of sheet; sprinkle top buns with half the mozzarella. (For 4 servings, leave potatoes roasting and add buns to a second baking sheet; toast on middle rack.) Return to oven until potatoes are tender, cheese is melted, and buns are lightly toasted, 3-5 minutes.

Divide buns between plates; fill with as many saucy meatballs as you like and sprinkle with remaining mozzarella. (TIP: The sandwiches are supposed to be messy, so don’t be afraid to pile them high!) Serve any extra meatballs and sauce on the side. Serve with potato wedges and garlic aioli for dipping.