In a large pot, bring salted water to a boil. Add the elbow macaroni and cook according to package instructions until al dente. Drain and set aside.
In a skillet, heat olive oil over medium heat. Add diced onion and sauté until softened, about 3 minutes. Add minced garlic and cook for an additional minute.
Add the ground beef to the skillet, breaking it up with a spatula. Cook until browned and fully cooked, about 5-7 minutes. Drain excess fat if necessary.
Stir in the taco seasoning, diced tomatoes (with juices), and beef broth. Bring the mixture to a simmer and cook for about 5 minutes, allowing the flavors to meld.
Reduce the heat to low, then add the cooked elbow macaroni, sour cream, and shredded cheddar cheese. Stir until the pasta is well coated and the cheese has melted, about 2-3 minutes.
Season with salt and pepper to taste. Remove from heat.
Serve hot, garnished with chopped fresh cilantro and sliced jalapeños if desired.