1/2 teaspoon salt
1/4 teaspoon baking soda
4 teaspoons water
12 ounces ground pork
2 slices hearty white sandwich bread, crusts removed, cut into 1/2-inch pieces
1/3 cup heavy cream
1/3 cup grated Parmesan cheese, plus extra for serving
2 large egg yolks
2 garlic cloves, minced
1 teaspoon fennel seeds, coarsely ground
1 teaspoon dried oregano
1 teaspoon pepper
1/2 teaspoon red pepper flakes
12 ounces sweet Italian sausage, casings removed, and broken into 1-inch pieces
2 tablespoons extra-virgin olive oil
1 garlic clove, minced
1 can (28 ounces) crushed tomatoes
1 can (15 ounces) tomato sauce
1 tablespoon minced fresh basil
1 pound spaghetti
Adjust oven rack to upper-middle position and heat oven to 500º F. Set wire rack in aluminum foil-lined rimmed baking sheet and spray with vegetable oil spray.
Dissolve salt and baking soda in water in large bowl. Add pork, fold gently to combine, and let stand for 10 minutes.
Pulse bread, cream, Parmesan, egg yolks, garlic, fennel seeds, oregano, pepper, and pepper flakes in food processor until smooth paste forms, about 10 pulses, scraping down sides of bowl as needed. Add pork mixture (do not wash out bowl) and pulse until mixture is well combined, about 5 pulses.
Transfer half of pork mixture to now-empty large bowl. Add sausage to processor and pulse until just combined, 4-5 pulses. Transfer sausage-pork mixture to bowl with pork mixture. Using your hands, gently fold together until mixture is just combined.
With wet hands, lightly shape mixture into 1 3/4 inch round meatballs; you should have about 24 meatballs. Arrange meatballs, evenly spaced, on prepared wire rack and bake until browned, about 15 minutes, rotating sheet halfway through baking.
While meatballs bake, heat oil in Dutch oven over medium heat. Add garlic and cook, stirring frequently, until fragrant, about 30 seconds. Stir in crushed tomatoes, tomato sauce, and 1/4 teaspoon salt, and bring to boil. Reduce heat and simmer gently until slightly thickened, about 10 minutes. Stir in basil and season with salt to taste.
Add meatballs to sauce and gently simmer, turning them occasionally, for 10 minutes. Cover and keep warm over low heat.
Bring 4 quarts water to boil in large pot. Add pasta and 1 tablespoon salt and cook, stirring often, until al dente. Reserve 1/2 cup cooking water, then drain pasta and return to pot.
Add 1/2 cup sauce and 1/4 cup reserved cooking water to pasta and toss to combine, adjusting consistency with remaining reserved cooking water as needed. Serve meatballs and sauce over pasta.