Heat oil in large nonstick skillet over medium high heat and cook chicken, turning once, 3 minutes.
Stir in onion and tomato and cook, stirring occasionally, until onion is tender, about 3 minutes.
Add water and Knorr® Homestyle Stock - Chicken to skillet and stir until Stock is melted. Bring to a boil over high heat. Reduce heat to low and simmer until chicken is thoroughly cooked, about 3 minutes. Arrange chicken on serving platter.
Stir in cheese and basil and cook until cheese begins to melt, about 1 minute. Serve sauce over chicken.