Step 1

Place bacon in processor. Using on/off turns, grind to coarse paste. Transfer to large bowl. Using garlic press, squeeze in garlic. Gently mix in beef and all remaining ingredients. Let stand 15 minutes.

Step 2

Line large rimmed baking sheet with plastic wrap. Using moistened hands and scant 2 tablespoonfuls for each, roll meat mixture into 1 1/2-inch meatballs. Arrange meatballs on sheet. DO AHEAD Can be made 1 day ahead. Cover with plastic wrap; chill.

Step 3

Puree tomatoes with juice and garlic in batches in blender until smooth.

Step 4

Cook bacon in large pot over medium heat until crisp; transfer bacon to plate.

Step 5

Add 1 tablespoon oil to drippings in pot and heat over medium heat. Add half of meatballs. Cook until brown on all sides, turning carefully with small metal spatula, about 9 minutes. Transfer meatballs to baking sheet. Add more oil to pot if needed and repeat with remaining meatballs.

Step 6

Increase heat to medium-high. Add onions and crushed red pepper to pot. Sauté until golden, about 6 minutes. Add wine; boil until reduced by half, stirring up browned bits, about 8 minutes. Add tomato puree and marjoram. Boil until sauce thickens slightly, stirring occasionally, about 8 minutes. Season with salt and pepper.

Step 7

Mix bacon into sauce. Add meatballs; bring to simmer. Reduce heat to low; cover and simmer until meatballs are heated through and tender, 10 to 15 minutes. Season sauce with salt and pepper.

Step 8

Meanwhile, cook spaghetti in pot of boiling salted water until just tender but still firm to bite, stirring occasionally. Drain; transfer to large bowl. Toss with 2 tablespoons oil and marjoram, adding more oil to moisten, if desired. Divide spaghetti among bowls. Top with meatballs and sauce. Sprinkle with cheese and serve, passing additional cheese separately.