Place chicken in a slow cooker. Coat with kosher salt, seasoned salt, black pepper, pepper flakes, and thyme. Pour chicken broth in and around the chicken. Cook on Low for 5 to 6 hours.

Shred chicken and place back into the broth. Add cream cheese and stir well to dissolve. Stir in ranch dressing. Add pasta and milk. Stir, place lid back on, and cook on High for 30 minutes.

In the meantime, place bacon in a large skillet and cook over medium-high heat, turning occasionally, until evenly browned, about 10 minutes. Drain bacon slices on paper towels.

Mix Cheddar cheese into pasta; crumble in bacon and stir to combine. Cook until cheese is melted and pasta is tender yet firm to the bite, about 10 minutes more.