In a skillet over medium heat, sauté the chopped yellow onion until translucent.

Add the minced garlic and cook for 30–60 seconds until fragrant.

Add the ground beef (or turkey) and cook until browned, breaking it apart as it cooks.

Drain excess fat if needed.

Stir in the jarred tomato sauce to the meat, bring to a simmer, and season with salt and pepper to taste.

Let simmer for 2–3 minutes to meld flavors.

Lightly grease the bottom and sides of a 6-quart slow cooker with nonstick spray or a thin layer of olive oil.

Spoon a thin layer of the meat sauce across the bottom of the crockpot.

Place broken or whole lasagna noodles over the sauce to cover as much surface as possible.

Dollop and spread some ricotta across the noodles, then sprinkle a layer of shredded mozzarella.

Continue layering sauce, noodles, ricotta, and mozzarella until you've used your ingredients, finishing with a generous layer of mozzarella on top.

Cover and cook on LOW for 3½–4 hours or on HIGH for 2–3 hours, checking after the minimum time.

Once cooked, turn off the crockpot and let the lasagna rest for 10–15 minutes.

Scatter chopped fresh basil (or parsley) over the top before serving.