SLOW COOKER METHOD
Heat oil in a skillet over medium heat. Add minced garlic and onion, sauté until the onion becomes soft and fragrant.
Transfer the chicken breasts, fire-roasted tomatoes, sautéed onion and garlic mixture, spices, warmed chicken stock, and salt into your preheated slow cooker.
Cover and cook on high for 3 hours.
Add the chopped bell pepper, half-and-half, cream cheese, and shredded cheddar cheese. Cook on high for an additional 20-30 minutes, until the cheese is melted and creamy.
Shred the chicken breasts inside the slow cooker using two forks.
Serve hot, garnished with fresh cilantro, sour cream, and avocado slices.

INSTANT POT METHOD
Set the Instant Pot to sauté mode and heat the oil.
Add garlic and onion and cook until softened and aromatic.
Stir in cumin, chipotle chili powder, oregano, and paprika; sauté for 30 seconds.
Add tomatoes and chicken stock, scraping the bottom of the pot to loosen any browned bits. Season with salt.
Place chicken breasts in the pot, seal the lid, and cook on high pressure for 8 minutes.
Allow a natural pressure release for 10 minutes, then release any remaining pressure manually.
Remove the chicken breasts and shred with forks.
Add bell pepper, cream cheese, cheddar cheese, and half-and-half to the pot; stir until melted and smooth.
Return shredded chicken to the pot, stir to combine.
Garnish with fresh cilantro before serving.