1. Heat the olive oil in a large, deep skillet or Dutch oven over medium heat. Add the chopped onion and sauté for about 3 minutes until soft and translucent.
2. Add the minced garlic and cook for another 30 seconds until fragrant—this always reminds me of the smells that filled my grandmother’s kitchen, a true sign that something delicious was on its way.
3. Add the ground beef to the pot. Break it up with a wooden spoon and cook until browned, about 6-8 minutes. Drain excess fat if necessary, especially if using higher-fat beef.
4. Sprinkle in the chili powder, cumin, smoked paprika, and cayenne pepper. Stir well to coat the meat and onions with the spices, letting the flavors develop for about a minute.
5. Pour in the uncooked macaroni, beef broth, and diced tomatoes with green chilies. Stir everything together and bring the mixture to a gentle boil.
6. Reduce the heat to low, cover the pot, and simmer for 10-12 minutes, stirring occasionally to prevent sticking. The pasta will cook right in the flavorful sauce, soaking up all those spices.
7. Once the pasta is tender and most of the liquid is absorbed, remove the pot from heat. Stir in the shredded cheddar and Monterey Jack cheeses along with the sour cream (or Greek yogurt). Mix until the cheese melts into a creamy sauce.
8. Taste and season with salt and pepper as needed. If the sauce feels too thick, add a splash of broth or milk to loosen it up.
9. Garnish with chopped cilantro or green onions for a fresh burst of color and flavor before serving.

From experience, stirring gently after adding the cheese is key to keeping it silky smooth. I learned this the hard way when my first batch clumped up—lesson learned! Also, don’t rush the simmering step; letting the pasta cook slowly in the broth infuses the dish with so much more flavor than boiling pasta separately.