Heat a large skillet over medium heat. Add olive oil and warm it up. Sauté the diced onion for 3-4 minutes until soft and translucent. Add minced garlic and ground beef, cooking until browned and fully cooked for 5-7 minutes. Drain excess fat.
While the beef is cooking, bring a pot of salted water to a boil. Add rotini pasta and cook until al dente, about 8-10 minutes. Drain and set aside, reserving a little pasta water.
In the same skillet, stir in the can of diced tomatoes with green chilies. Add softened cream cheese, chili powder, cumin, salt, and pepper. Stir until cream cheese melts and mixture is well combined, about 3-5 minutes.
Add the cooked rotini pasta to the skillet with the creamy beef mixture. Toss gently to coat. If the sauce is too thick, add reserved pasta water to adjust consistency.
Sprinkle shredded cheddar cheese over the top. Cover the skillet and let it sit for a few minutes to melt the cheese. Garnish with fresh cilantro or parsley if desired.