Bring a large pot of salted water to a boil. Cook penne until al dente. Reserve ½ cup pasta water, then drain.
In a large skillet, heat olive oil over medium heat. Cook chicken until golden and fully cooked. Remove and dice or shred.
In the same skillet, add garlic and sauté until fragrant.
Lower heat and stir in cream cheese and milk (or broth) until smooth.
Add cheddar cheese and ranch seasoning. Stir until melted and creamy.
Return chicken and bacon to the skillet. Stir to combine.
Add cooked pasta and toss gently, adding reserved pasta water as needed.
Taste and adjust seasoning. Serve hot with optional garnishes.