Cook and crumble the ground beef in a large skillet over medium-high heat for 6-7 minutes. Drain grease and return to heat. Stir in the beef broth and taco seasoning and bring to a boil. Reduce to a simmer and cook for 2-3 minutes. Remove and set aside.
Begin boiling a pot of water for the pasta. When the pasta reaches a boil, salt it generously. (I use 3/4 tbsp. Kosher salt.)
Add the reserved diced tomato juice to the skillet and use a silicone spatula to clean the bottom and sides of the skillet. Reduce the liquid by half.
Add the onions and butter and cook for 5 minutes. Stir in the tomato paste and garlic and cook for 3 minutes.
Add the diced tomatoes. Slowly stir in the sauce mixture (from step 1 of prep work). Bring to a boil, then reduce to a simmer.
Stir the taco meat into the sauce and simmer, uncovered, while you boil pasta according to package instructions. Drain once cooked.
Reduce heat to low. Add the cream cheese and gradually sprinkle in the cheddar cheese, stirring continuously, until incorporated.
Add the drained pasta (I like to add slightly less than ¾ lb. for extra saucy pasta)!
The sauce will thicken and the spaghetti will continue to absorb the sauce upon standing.
Garnish with chopped cilantro and serve!