Preheat oven to 375 degrees F. Spray a large baking dish with nonstick cooking spray and set aside.
Cook the pasta. Bring a large pot of salted water to a boil. Add the pasta and cook until al dente. Reserve 1-2 cups of the salted pasta water; drain well.
Prepare the cream sauce. As the noodles are cooking, add the olive oil to a large pan or Dutch oven over medium heat. Add the onion and cook, stirring often, for 4-5 minutes, or until soft and translucent. Add the garlic, salt, and pepper, mixing well to combine. Cook for 1 minute. Add the butter, cream cheese, chicken broth, hot sauce, and Ranch dressing to the onions. Mix continuously until cream cheese is melted.
Add the chicken. Add the cooked chicken to the sauce and mix to combine.
Add the cheese and cooked noodles. Add one cup of the cheddar cheese and one cup of the mozzarella cheese to the pot. Mix thoroughly to combine. Gently fold in the cooked and drained noodles. NOTE: If your sauce is thicker than you'd like, thin using the reserved pasta water from step 1. Start with approximately half a cup and add more as needed.
Transfer to prepared baking dish. Season with additional salt, pepper, or hot sauce, to taste then transfer the chicken and pasta mixture to your prepared baking dish. Top with spoonfuls of ricotta cheese, chopped green onions, and sprinkle with the remaining shredded cheese. Drizzle with additional hot sauce or Ranch dressing, if desired.
Bake. Transfer to your preheated oven and bake for 15-25 minutes, or until cheese is melted and bubbly.
Serve garnished with additional green onion, hot sauce, or Ranch dressing, if desired.