Heat 2 tablespoons oil in 10-inch skillet and cook onion, stirring occasionally, 5 minutes or until tender. Stir in garlic and cook 30 seconds; cool slightly.
Process onion mixture, chipotle pepper, sauce, tomato puree and Knorr® Chicken flavor Bouillon in food processor or blender until smooth.
Cook tomato mixture in 4-quart saucepot over medium-low heat, stirring frequently, 15 minutes or until slightly thickened. Whisk in 3/4 cup Hellmann's® or Best Foods® Real Mayonnaise. Remove from heat and keep warm.
Preheat oven to 350°. Combine chicken, remaining 1/4 cup Mayonnaise and 1 cup cheese in medium bowl; set aside.
Heat remaining 6 tablespoons oil in 10-inch nonstick skillet over medium heat and cook tortillas, one at a time, turning once, 1 minute or until heated through but not crisp. Drain on paper towels.
Spread 1/2 cup sauce in 13 x 9-inch baking dish. Dip tortillas in remaining sauce, then fill each with about 1/4 cup chicken mixture. Roll and place seam-side down in baking dish. Pour remaining sauce over enchiladas, then sprinkle with remaining 1/2 cup cheese.
Bake 20 minutes or until enchiladas are heated through and cheese is melted. Garnish, if desired, with additional chopped onion.