Place chicken breasts in a single layer in a 4-quart or larger slow cooker. Set softened cream cheese on top.
Sprinkle the ranch packet over everything. Cover and cook on low for 6 hours.
While chicken cooks, cook bacon until crisp, then cool and crumble.
Shred the chicken into the cream cheese sauce with two forks or a hand mixer on low.
Add shredded cheddar and crumbled bacon. Cover and let sit on warm for 15 minutes, until cheese melts.
Stir to combine, scatter green onions over the top, and serve hot on buns.
Notes
Soften the cream cheese so it melts evenly. Cook the bacon before adding it because raw bacon does not render well in the slow cooker. Toast the buns so they hold up to the creamy filling. A hand mixer on low can shred the chicken quickly right in the crockpot.