Season chicken with salt and pepper, rub chicken with basil pesto.
Heat olive oil in a large nonstick skillet.
Add chicken to skillet and cook for 5 minutes on each side, or until thoroughly cooked.
In the meantime, prepare the sauce by combining flour, garlic, basil pesto, evaporated milk, broth or wine, salt and pepper in a small bowl; whisk until thoroughly combined and set aside.
Remove chicken from skillet, set aside.
Prepare spaghetti noodles according to package directions.
Add the prepared sauce to the skillet and bring to a boil. Reduce sauce to low and simmer 5 minutes. Whisk in lemon juice.
Place chicken back in the skillet and cook for 5 minutes. Sprinkle each chicken breast with shredded mozzarella cheese, cover. Heat until cheese has melted and chicken is heated through, about 5-8 minutes longer. Remove from heat.
Serve with cooked spaghetti noodles
Garnish with basil ribbons, optional