In a large bowl, combine the ground beef, egg, salt, black pepper, garlic, basil, milk, Parmesan, and breadcrumbs. Use your hands to mix until combined. Roll into ½-inch round meatballs.

Heat the olive oil in a large, deep skillet or braiser over medium-high heat. Working in batches as necessary, add the meatballs and cook until browned all over, about 2 minutes per side. They don’t have to be completely cooked through, but they should be nicely browned. Transfer to a clean plate and set aside.

Reduce the heat to medium-low and add more oil to the skillet, if needed. Add the onion and garlic. Cook, stirring, until tender, about 3 minutes. Pour in the marinara and broth. Stir to combine. Add the basil, parsley, coconut sugar, Parmesan, and salt. Stir until well combined. Bring to a gentle simmer over medium to medium-low heat, 3 to 4 minutes.

Pour in the pasta and cook, stirring frequently, until the pasta is very al dente and has absorbed a lot of the sauce, 8 to 10 minutes. The pasta easily sticks to the bottom if you leave it simmering without stirring, so don’t leave it unattended and lower heat as needed.

Add the meatballs and any of their juices back into the pot. Stir to combine. Continue to cook, stirring frequently, until the meatballs are fully cooked through and the pasta is tender, about 6 minutes.

Remove from heat, cover, and let rest for about 2 minutes before serving. This just helps the pasta soak up the sauce a little more and settle!

Remove from heat, garnish with more basil and crushed red pepper flakes, if using, and serve!