With a large spoon or spatula, mix together all the meatball ingredients in a large bowl until just combined—avoid overmixing.

Scoop a portion of the mixture, about 2 Tablespoons (30–35g) in size, roll into a ball with your hands, and place on a baking sheet or large plate lined with parchment paper. Repeat with remaining mixture. You should have around 30–34 meatballs. Set aside.

Grease a (4-quart or larger) slow cooker with nonstick spray (or a drizzle of olive oil). Place the onions in the slow cooker, then pour 1 can of crushed tomatoes over top of the onions. Add in the tomato paste and garlic, and stir gently to combine.

Heat a large skillet over medium-high heat, and then add in a Tablespoon of olive oil and swirl to coat. Working in batches, sear the meatballs (about 6–8 meatballs at a time, or however many fit in your skillet) for about 1 minute on each side, until browned. Place the browned meatballs in the slow cooker. Once all browned meatballs have been added to the slow cooker, pour the remaining can of crushed tomatoes on top, and add in the crushed red pepper flakes and bay leaves.

Cover with the lid and cook on low for 6–7 hours. (You can also cook on high for about 4 hours if that works better for your day.) Remove and discard the bay leaves.

Serve warm meatballs with sauce over your choice of pasta, in a sub roll, or on their own. Top with chopped basil, parsley, or fresh parmesan cheese, if desired.

Store leftovers covered tightly in the refrigerator for up to 1 week.