Cook the pasta: Bring a large pot of salted water to a boil. Cook the whole-wheat fettuccine until al dente. Reserve 1/2 cup pasta water, then drain and set aside.

Season the chicken: Pat chicken dry. Toss with 1/2 teaspoon chili powder, 1/2 teaspoon cumin, 1/4 teaspoon smoked paprika, a pinch of salt, and pepper.

Sear the chicken: Heat 1/2 tablespoon olive oil in a large skillet over medium-high. Add chicken in a single layer and cook 4–6 minutes, stirring once, until just cooked through. Transfer to a plate.

Sauté the veggies: In the same skillet, add remaining 1/2 tablespoon olive oil and the butter. Add onion and bell pepper; cook 3–4 minutes until softened. Stir in corn, garlic, remaining spices, and lime zest; cook 1 minute until fragrant.

Build the lighter roux: Sprinkle flour over the veggies. Cook 30–45 seconds, stirring to coat.

Add liquids: Slowly whisk in chicken broth, then milk, smoothing out any lumps. Bring to a gentle simmer and cook 3–4 minutes, stirring, until slightly thickened.

Melt and enrich: Reduce heat to low. Stir in cream cheese until melted and smooth. Add Parmesan and stir until the sauce is silky.

Stabilize with yogurt: In a small bowl, whisk Greek yogurt with a few spoonfuls of hot sauce from the pan to temper it. Stir the tempered yogurt into the skillet over low heat. Do not boil.

Add greens and chicken: Stir in spinach until wilted. Return chicken and any juices to the pan. Simmer 1–2 minutes. Add lime juice and adjust salt and pepper.

Toss with pasta: Add drained pasta to the skillet and toss until coated. If needed, splash in reserved pasta water to loosen the sauce to your liking.

Finish and serve: Sprinkle with cilantro. Add optional toppings like avocado or jalapeño. Serve warm.