Step 1: Brown the Ground Beef

1. In a skillet over medium heat, cook the ground beef until browned and fully cooked, breaking it into small crumbles.
2. Add the diced onion and minced garlic, cooking for another 2-3 minutes until fragrant and the onion is softened.
3. Drain excess fat and transfer the mixture to the slow cooker.

Step 2: Add the Base Ingredients

1. Stir in the taco seasoning, diced tomatoes with green chilies, tomato sauce, broth, and water. Mix well to combine.

Step 3: Slow Cook the Base

1. Cover the slow cooker and cook on low for 2-3 hours or on high for 1 hour. This allows the flavors to meld before adding the pasta.

Step 4: Add the Spaghetti

1. Break the spaghetti in half and stir it into the slow cooker, ensuring it is submerged in the liquid.
2. Cook for an additional 1-1.5 hours on low or 30-45 minutes on high, stirring occasionally to prevent the pasta from sticking together.

Step 5: Add Cheese

1. Once the spaghetti is tender, sprinkle the shredded cheddar and Monterey Jack cheese over the top.
2. Cover and let the cheese melt for 5-10 minutes.

Step 6: Serve and Garnish

1. Stir the melted cheese into the spaghetti for a creamy texture or leave it on top for a gooey finish.
2. Serve hot, garnished with your favorite toppings like cilantro, sour cream, or crushed tortilla chips.