Bring a large pot of salted water to a boil and cook pasta until al dente. Reserve 1/2 cup pasta water, then drain. In a large skillet over medium heat, add olive oil and minced garlic. Cook for 30 seconds until fragrant. Pour in heavy cream and chicken broth and bring to a gentle simmer. Stir in ranch seasoning, salt, and black pepper. Reduce heat to low and add shredded cheddar and Parmesan cheese gradually, stirring until melted and smooth. If sauce becomes too thick, add reserved pasta water a little at a time. Stir in cooked chicken and crumbled bacon and simmer for 2–3 minutes. Add drained pasta to the skillet and toss until evenly coated. Garnish with fresh parsley and serve warm.