Heat large skillet over medium heat. Add chopped bacon and cook 6-8 minutes until crispy. Remove bacon with slotted spoon and set aside on paper towels, leaving rendered fat in pan.
Season chicken pieces with salt, pepper, garlic powder, onion powder, and smoked paprika.
Increase heat to medium-high. Add seasoned chicken to bacon fat in single layer. Sear 3-4 minutes without moving, then flip and cook additional 3-4 minutes until internal temperature reaches 165°F.
Meanwhile, cook pasta according to package directions until al dente. Reserve 1 cup pasta water before draining.
Add chicken broth to skillet with chicken, scraping up any browned bits. Whisk in ranch dressing mix until completely dissolved.
Reduce heat to medium-low. Gradually add heavy cream, whisking constantly to prevent lumps.
Add drained pasta to skillet and toss to coat. Gradually stir in cheddar and Parmesan cheeses until melted and creamy.
If sauce seems too thick, add reserved pasta water 1/4 cup at a time until desired consistency is reached.
Remove from heat. Stir in three-quarters of the cooked bacon. Taste and adjust seasoning.
Serve immediately, garnished with remaining bacon and fresh chives.