Cook the pasta. Bring a large pot of salted water to a boil. Cook pasta to al dente according to package directions. Reserve 1/2 cup pasta water, then drain and set aside.

Crisp the bacon. In a large skillet over medium heat, cook bacon until crisp. Transfer to a paper towel–lined plate. Pour off most of the grease, leaving about 1 tablespoon in the pan.

Cook the chicken. Cut chicken into bite-size pieces. Season with salt and pepper. Add olive oil to the skillet, then cook chicken over medium-high heat until browned and cooked through, 6–8 minutes. Remove to a plate.

Start the sauce. Lower heat to medium. Add butter to the skillet. Stir in garlic and cook 30 seconds until fragrant. Sprinkle in flour and whisk for 1 minute to make a roux.

Add liquids. Slowly whisk in chicken broth until smooth, then add milk or half-and-half. Simmer 2–3 minutes, stirring, until slightly thickened.

Make it ranchy and creamy. Whisk in cream cheese until melted and smooth. Stir in ranch seasoning and Parmesan. If the sauce seems too thick, splash in reserved pasta water until it reaches a silky consistency.

Combine everything. Add cooked pasta, chicken, and crumbled bacon to the skillet. Toss to coat. Taste and adjust with salt, pepper, or extra ranch seasoning as needed.

Finish and serve. Stir in optional veggies (peas, spinach, or broccoli) until warmed and tender. Garnish with chopped parsley or chives. Serve hot.