Bring a large pot of salted water to a boil. Cook the pasta according to package instructions until al dente. Reserve ½ cup of pasta water, then drain and set aside.In a large skillet over medium heat, cook the chopped bacon until crispy. Remove the bacon with a slotted spoon and drain on paper towels. Leave about 1 tablespoon of bacon grease in the pan.
Add olive oil to the skillet with the reserved bacon grease. Season the diced chicken with salt, pepper, and garlic powder, then add to the skillet. Cook until golden and cooked through, about 6–8 minutes. Remove from pan and set aside.
Reduce heat to low. Pour the heavy cream into the skillet and stir in the ranch seasoning mix. Simmer for 2–3 minutes, then add in cheddar and Parmesan cheese. Stir until melted and smooth. If the sauce is too thick, add a splash of the reserved pasta water to loosen.
Return the cooked pasta, chicken, and bacon to the skillet. Toss everything together until well coated in the sauce. Cook for another minute or two to let flavors blend.
Serve hot, topped with chopped parsley for a fresh finish, if desired.