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 batter into pan.
Bake as directed on box for 13x9-inch pan. Cool 15 minutes.
Meanwhile, in 2-quart saucepan, mix glaze ingredients. Heat to boiling over high heat, stirring frequently. Reduce heat to medium; continue to boil 3 minutes, stirring frequently, until glaze has thickened slightly.
Poke warm cake every inch with fork tines. Pour glaze slowly over cake. Cool completely, about 1 hour.
In small bowl, beat whipping cream and powdered sugar on high speed until soft peaks form. Garnish each serving with whipped cream, mint leaf and shredded lime peel. Store loosely covered.