Cook pasta according to the package directions. Once cooked, rinse pasta in a colander and set aside.

Meanwhile, place a large cast iron skillet over medium heat. Add bacon and cook until crispy.

Remove bacon and pat dry with paper towels. Drain most of the bacon grease from the pan, but leave about 1 tablespoon of grease in the pan.

Add garlic, onion and diced chicken to the skillet. Cook over medium-high heat, stirring occasionally, until chicken is fully cooked (~9-10 minutes).

In a small bowl, whisk together the ranch dressing mix and milk. Add milk and diced tomatoes to the skillet; stir until well combined.

Continue cooking over medium heat, stirring occasionally, until mixture has reduced in volume and thickened noticeably (~18-20 minutes).

Add the cooked pasta, sour cream, pepper jack cheese and bacon; stir until cheese has fully melted.

Garnish with sliced green onions before serving (optional).