1. In a skillet over medium heat, brown the ground beef until fully cooked. Drain any excess fat.

2. Transfer the cooked beef to the slow cooker.

3. Add the marinara sauce, chopped onion, and minced garlic to the slow cooker.

4. Stir the ingredients together until well combined.

5. Cover and cook on low for 6-8 hours or on high for 3-4 hours.

6. Taste and adjust seasoning with salt and pepper if needed before serving.

For a spicier sauce, add a pinch of red pepper flakes or a splash of hot sauce. You can also incorporate additional vegetables, such as bell peppers or mushrooms, for more texture and flavor. If you prefer a creamier sauce, stir in a splash of heavy cream or a dollop of ricotta cheese just before serving. For a vegetarian version, substitute the ground beef with a plant-based meat alternative or simply omit it and add more vegetables.