Place the boneless skinless chicken breasts in the slow cooker, spreading them out in an even layer for uniform cooking. Add a lid and keep the cooker closed so the temperature stays steady.

Add the cream of chicken soup, cream of mushroom soup, Rotel diced tomatoes with green chilies, chicken broth, onion, diced, and green bell pepper, diced. Sprinkle in garlic powder, onion powder, salt, and black pepper, then press everything down gently into the liquid.

Cook on low for 6–7 hours or high for 3–4 hours until the chicken is tender and easily shreds with minimal resistance. Visual cue: the surface should be bubbling around the edges and the chicken should look fully cooked.

Remove the chicken from the slow cooker and shred it with two forks until you have bite-size pieces. Return the shredded chicken to the slow cooker.

Add the spaghetti, cooked and drained and the shredded Velveeta or sharp cheddar cheese to the slow cooker. Stir until the pasta is submerged and the cheese starts to melt into the sauce.

Stir everything together until the cheese is fully melted and the pasta is evenly coated. Visual cue: the sauce should look creamy and glossy with no unmelted cheese lumps.

Serve hot directly from the slow cooker. Visual cue: a scoop should show creamy sauce strands clinging to the spaghetti and shredded chicken.