Brown the ground beef in a deep pan or a large Dutch oven set over medium-high heat. Crumble the meat into smaller and smaller pieces until it is completely cooked, about 8 minutes. Drain the grease then set the beef aside for later.
Add two tablespoons of oil to the same pan that was used to cook the ground beef. Add the diced onion and cook until translucent, about 5 minutes.
Add the minced garlic, jalapeño (if using), tomato paste, chili powder, salt, oregano, cumin, and black pepper, and cook until fragrant, about 1 minute. Add the can of Rotel to the onions and spices, mixing well to combine.
Add the dried spaghetti noodles to the pan (there's no need to mix) and top with the beef broth. The pasta should be covered by broth; if necessary add one additional cup of beef broth.
Increase the heat to high and bring just to a boil. Once it reaches a boil, reduce the heat to medium-low and let it simmer for approximately 8-10 minutes or until the spaghetti is cooked to al dente (stir everything together about halfway through cooking).
Stir in the cooked beef and Mexican crema, then remove from heat. Cover with a lid and allow the pasta to rest for approximately 5 minutes. This allows enough time for the flavors to meld and for everything to reach the same temperature.
Finally, add the shredded cheese and stir until melted. Garnish with jalapeño slices, green onions, and freshly minced cilantro if desired.