Preheat your oven to 375°F. Grease a 9×13-inch baking dish. Boil salted water and cook pasta until al dente, then drain.: You will notice the oven warming the kitchen and a gentle hum as it reaches 375°F , which ensures even baking. The salted boiling water seasons the penne pasta from the inside, and cooking to al dente leaves a firm bite that holds up after mixing with the sauce and baking. Drain promptly to avoid the pasta soaking up excess water, which can make the casserole watery. A common mistake is overcooking the pasta, which leads to a mushy final texture; aim for a slight resistance when you bite the pasta and stop cooking immediately, then drain and set aside.
Season the chicken cubes with salt, pepper, garlic powder, onion powder, and smoked paprika. In a large skillet over medium heat, heat a small amount of oil and sauté the chicken pieces until they are fully cooked, reaching an internal temperature of 165°F. Set aside.: As the chicken hits the hot skillet it should sizzle softly and pick up golden brown edges, adding savory fond that boosts flavor. Even seasoning ensures every cube tastes balanced, and the smoked paprika gives a warm color and subtle smoke. Cooking to 165°F guarantees safety and juiciness; undercooked pieces are unsafe, and overcooking will dry them, so use an instant read thermometer. A frequent slip is overcrowding the pan, which causes steaming rather than browning; cook in batches if needed for crisp, caramelized bits.
In a bowl, whisk Buffalo wing sauce, cream cheese, ranch dressing, and Greek yogurt until smooth.: As you whisk, the cream cheese should soften and meld into the hot sauce, creating a glossy, cohesive emulsion. The aroma will shift from sharp vinegar notes of the Buffalo sauce to a creamier, tangy scent as ingredients blend. Smoothness matters, because lumps of cream cheese will give pockets of uneven texture. If separation occurs, temper by whisking in a tablespoon of warm water slowly. Avoid using cold cream cheese straight from the fridge, which resists emulsifying.
Combine the browned chicken and drained pasta with the sauce. Stir gently until everything is well-coated, then add in the shredded mozzarella cheese and mix to combine.: When you fold the elements together, you should see every ridge of penne pasta pick up the orange, creamy sauce, and the mozzarella cheese will begin to soften into strings that knit the mixture. The smell becomes rich and tangy, with dairy notes mellowing the heat. Gentle folding preserves the integrity of the chicken cubes and keeps the pasta from breaking; vigorous stirring can shred the pasta and make the casserole gluey. A common oversight here is adding the cheese too early to a hot pan, which can overmelt and become greasy; add and fold just until integrated.
Transfer the mixture into the prepared baking dish. Sprinkle the shredded cheddar cheese evenly on top. Bake in the preheated oven for 25-30 minutes until the casserole is bubbly and the cheese is melted.: As the casserole slides into the oven, aromas will start to bloom, and within 10 minutes you will hear a soft bubble as the sauce warms through. The top will transition from glossy to gently domed, and the cheddar cheese will melt into a golden, cohesive layer that signals readiness. Baking for the recommended time ensures the interior is steaming and the edges set without drying out. Overbaking can cause the cheese to separate and the texture to become dry, so watch for steady bubbling and melted, but not scorched, cheese. Rotate the dish halfway if your oven has hot spots to ensure even melting.
Remove the casserole from the oven. Garnish with sliced green onions and serve warm.: Once out of the oven, steam should rise in a fragrant ribbon, carrying creamy, tangy notes. Letting it rest a few minutes allows the sauce to set slightly, making scooping cleaner and preserving the layered textures. The thinly sliced green onions add a bright, crisp finish and a fresh onion perfume that cuts through richness. A common error is serving immediately; the casserole will be too loose and hard to portion, so rest for a short time to achieve the best balance of creaminess and structure.
