Make the sauce. Tear 5 of the basil leaves in half; reserve the rest. Combine the torn basil, olive oil, garlic, and crushed red pepper, if using, in a small pan and heat over very low heat, allowing the basil and garlic to “steep” in the olive oil for 10 to 15 minutes. The oil will become fragrant and rich with flavor—be careful to not let the garlic burn or go beyond a medium-brown color. Remove from the heat, strain the aromatics, and set the oil aside.
Combine the crushed tomatoes and 2 cups (480 ml) of water in a large pot. Add the tomato paste, salt, and pepper. Pour in the infused oil and stir to combine. Bring to a boil over medium-high heat, then immediately reduce to a simmer. Remove ½ cup (120 ml) of the brodo for the meatballs, setting aside to cool.
Partially cover the pot and simmer for 1 hour.
Make the meatballs. In a large bowl, handmix all the meatball ingredients. (This prevents overmixing.) The mixture will be very soft, but resist the urge to add more bread crumbs; you’re making tender, melt-in-your-mouth meatballs. Once all the ingredients are combined, wet your hands and pinch off a golf-ball sized piece of the mixture (about ¼ cup) and roll it into a ball. Place each meatball on a baking sheet and repeat with the remaining mixture, making approximately 16 to 18 meatballs.
Carefully drop the meatballs into the sauce. If the pot seems too full, shimmy the pot back and forth to make more room. (Do not stir with a spoon—you will break the meatballs!)
Simmer the meatballs in the sauce for 45 minutes or up to 2 hours. The longer it cooks, the better it tastes. Carefully remove the meatballs to a plate. Chop the remaining basil and sprinkle on top of the sauce. Serve with Tagliatelle or the pasta of your choice.