Heat the olive oil in a skillet over medium heat, and cook the chicken for about 5 minutes, until lightly browned. Mix the garlic and sherry into the skillet. Cook and stir until all the liquid has been reduced and the chicken is no longer pink and juices run clear.
Mix the pine nuts into the skillet, and cook 2 to 3 minutes over medium heat. Reduce the heat to low, and mix in the basil, sour cream, Parmesan cheese, and pepper. Continue cooking until heated through.
