Heat oven to 350°F (325°F for dark or nonstick pan). Spray bottom only of 13x9-inch pan with baking spray with flour.
In large bowl, beat cake ingredients with electric mixer on low speed 30 seconds, then on medium speed 2 minutes, scraping bowl occasionally. Pour into pan.
Bake 27 to 33 minutes or until toothpick inserted in center comes out clean. Cool 5 minutes. With handle of wooden spoon (1/4 to 1/2 inch in diameter), poke holes almost to bottom of cake every 1/2 inch, wiping spoon handle occasionally to reduce sticking.
In medium bowl, stir together filling ingredients (mixture will thicken). Pour over cake; spread evenly over surface, working back and forth to fill holes. (Some filling should remain on top of cake.) Refrigerate 1 hour.
Spread frosting over cake; sprinkle with lime peel. Garnish as desired. Store loosely covered in refrigerator.