Step 1: Mix the Meatball Ingredients - Grab a large mixing bowl and add the ground beef, uncooked rice, finely diced onion, eggs, salt, pepper, garlic powder, onion powder, and Worcestershire sauce. I like to use clean hands for this part because you can feel when everything is mixed without mashing it too much. The goal is to combine the ingredients gently until they are evenly blended. If you overwork the beef, the meatballs can turn out firm instead of tender, and nobody wants a tough meatball after waiting all day for dinner.
Step 2: Roll the Meatballs - Once the mixture is combined, roll it into medium meatballs. I usually aim for meatballs that are big enough to feel hearty but not so large that the rice struggles to cook through. Place them in the bottom of the slow cooker in as even a layer as you can manage. It is fine if a few are touching, but try not to pack them in too tightly. Giving them a little room helps the sauce move around them while they cook.
Step 3: Stir Together the Tomato Sauce - In a separate bowl, whisk together the tomato sauce, diced tomatoes, beef broth, brown sugar, Italian seasoning, and minced garlic. This sauce is simple, but it does a lot of work. The tomato sauce gives body, the diced tomatoes add texture, the broth helps cook the rice, and the brown sugar softens the tomato tang. Give it a good stir so the garlic and seasonings are spread throughout.
Step 4: Pour the Sauce Over the Meatballs - Pour the tomato sauce mixture evenly over the meatballs in the slow cooker. Try to cover them as much as possible so every meatball gets that rich tomato flavor while it cooks. I usually use a spoon to nudge the sauce around a bit, but do not stir aggressively because the meatballs are still raw and tender at this point. Just let the sauce settle in around them.
Step 5: Slow Cook Until Tender - Cover the slow cooker and cook on low for 5 to 6 hours or on high for 3 to 4 hours. Low is my favorite when I have the time because the meatballs become especially tender and the sauce gets that deep, cooked all day flavor. The meatballs are done when the beef is cooked through and the rice is tender. You will see those little rice pieces poking out, which is the fun part of porcupine meatballs.
Step 6: Spoon the Sauce and Finish With Parsley - Before serving, gently spoon some of the tomato sauce over the meatballs. This gives them a nice glossy finish and makes sure every bite is saucy. Sprinkle chopped parsley over the top right before serving. It may seem like a small thing, but that little bit of green makes the whole dish look fresh and ready for the table.