Preheat the oven to 350 degrees.
In a medium bowl, combine the breadcrumbs and milk. Let sit for 4 minutes, then whisk in the egg. Add the beef, pork, cheese, garlic powder, Italian seasoning, salt, onion powder, and black pepper. Mix gently until combined. Do not overmix.
In a large skillet set over medium heat, add the olive oil. When the oil is hot, form the mixture into meatballs and place into the skillet to cook. Brown on all sides. The meatballs should be fully cooked.
Meanwhile, cook the pasta according to the package's directions. Drain and set aside.
Remove the meatballs from the skillet and transfer to a lined plate. Add the garlic and saute until fragrant. Pour in marinara, return the meatballs to the skillet. Simmer on medium low heat for 15 minutes.
Stir in cooked spaghetti, along with 1/2 cup of the mozzarella and 1/4 cup of the parmesan cheese.
Sprinkle remaining cheeses over top. Place in the oven and bake for 30 minutes.
Remove from the oven and allow to set for 10 minutes before serving.