Dice the chicken breasts into little pieces. Season the chicken breasts with the Mrs. Dash seasoning, salt, and pepper. Let the chicken marinate for at least 2 hours (preferably overnight).
Heat a few tablespoons of olive oil in pan. Once oil is hot add the chicken to the pan. Brown the chicken.
Cook pasta according to the box instructions provided for the pasta. While the pasta is cooking, place a medium to large saucepan on low heat. Add butter to this pan. Once the butter has melted, add the Velveeta cheese to the saucepan. Cook this cheese sauce on low heat stirring frequently. While the cheese is melting, add the milk to the cheese sauce 1/3 cup at a time until desired consistency.
After pasta has cooked, drain the pasta. Once the cheese has melted, mix the pasta, cheese sauce, chicken, garlic powder, and spinach together in the large pot. Continue to add milk to the pasta to get the desired consistency of the cheese sauce. Salt and pepper to taste.