Preheat the oven to 350 degrees F (175 degrees C). Coat a 9x13-inch baking dish with cooking spray.
Bring a large pot of lightly salted water to a boil. Cook bow-tie pasta at a boil, stirring occasionally, until tender yet firm to the bite, about 12 minutes.
Meanwhile, melt butter in a saucepan over medium heat. Add cream cheese and ranch mix; whisk until smooth. Slowly whisk in milk. Stir in Monterey Jack; cook until melted and sauce thickened, 5 to 10 minutes. Crumble in 6 strips bacon; stir to combine.
Combine pasta and chicken together in a large bowl. Pour in sauce and mix until well combined; transfer to prepared baking dish. Sprinkle on Cheddar Jack; crumble remaining 2 strips bacon on top.
Bake in the preheated oven until cheese melted, about 20 minutes.
