Prepare the sauce first. Note that spaghetti sauce can be cooked ahead of time and refrigerated until ready to use. If using prepared pasta sauce, this dish will only take about 45 minutes.
Chop onions and carrots into small pieces so it doesn't take too long to cook through. Preheat a pot over medium heat and add olive oil. Saute veggies for a few minutes.
Add smashed garlic and saute until fragrant. Pour in the entire can of crushed tomatoes and add bay leaves, oregano, sugar, and salt.
Stir everything together, cover, and let it cook for about 20 minutes. Stir the sauce from time to time. Add fresh basil and cook, covered, for another 20 minutes. Remember to stir occasionally.
Remove bay leaves and blend the sauce in a food processor. Set aside.
Meatballs:
Use a large, 12-inch skillet that is also oven-safe. (Or, you can also use a separate 9×13 casserole dish just for baking.)
Combine ground beef, ground pork, egg, minced onion, pressed garlic, herbs, salt, and pepper in large mixing bowl.
Drench a slice of bread in milk, squeeze it out, break it up into crumbs, and add it to the bowl as well. Mix everything very well.
Use a larger cookie scoop to scoop out even amounts of meat mixture and shape the meatballs.
Preheat the skillet over medium heat, add oil, and sear meatballs for a few minutes on each side.
Add the sauce, lower the heat to medium-low, and cook meatballs until just done.
Spaghetti and Meatballs Bake:
Note: Cook pasta at the same time as cooking the meatballs. Make sure pasta is cooked al dente, don't overcook it. Drain and set aside.
Preheat the oven to 375°.
Take meatballs out of the pan but leave the sauce. Add spaghetti to the pan with sauce and mix well to coat all the pasta with sauce.
Nestle meatballs into the spaghetti and top everything off with shredded cheese and a sprinkle of oregano.
Place the skillet into the oven and bake for about 10-15 minutes.