While you're gathering ingredients, cook the bacon in a skillet over medium heat until crispy, about 8-10 minutes. Drain on paper towels and chop into 1/2-inch pieces. Meanwhile, cut the chicken breasts into 1-inch chunks and dice the celery, onion, and carrots into roughly equal sizes so they cook evenly. Remove the cream cheese from the refrigerator to soften to room temperature—this prevents clumping when added to the hot soup later. I like to prep all my vegetables while the bacon cooks so everything is ready to go.
Add the raw chicken chunks, cream of chicken soup, ranch dressing mix, diced vegetables, and chicken broth to your slow cooker. Stir well to combine and ensure the ranch mix is evenly distributed throughout the liquid. Cover and cook on low for 4-6 hours, until the chicken is completely cooked through and the vegetables are tender.
Remove the cooked chicken from the slow cooker using a slotted spoon and transfer to a cutting board. Shred it into bite-sized pieces using two forks or a potato masher, then return it to the pot. Increase the slow cooker to high heat. Add the cooked bacon, shredded cheddar cheese, and softened cream cheese to the pot, stirring constantly until the cream cheese is fully melted and incorporated into the soup. The heat will help the cheese melt smoothly without clumping.
Stir the frozen tortellini directly into the soup without thawing—they'll cook right in the hot broth. Cook on high for 30-60 minutes, stirring occasionally, until the tortellini are tender and floating. I find that about 40 minutes works best for most frozen tortellini, but check the package instructions and start testing at 30 minutes. The soup will thicken slightly as the tortellini cook and release their starches.
Give the soup a taste and adjust the seasoning with salt, pepper, or additional garlic powder if needed. The ranch mix and cream cheese contribute a lot of salt, so taste before adding more. Ladle the soup into bowls and serve hot, optionally garnished with fresh herbs like chives, parsley, or green onions if desired.