Heat oven to 350. Spray bottom of 13x9 pan with baking spray (with flour).
Beat cake ingredients in large bowl on low speed for 30 seconds; increase to medium speed and beat 2 minutes. Pour batter into prepared pan; bake about 30 minutes, or until a toothpick inserted in center comes out clean. Cool 15 minutes.
Meanwhile, mix glaze ingredients in a medium saucepan and heat to boiling over high heat, stirring frequently. Reduce heat to medium, boil for another 2 minutes, stirring frequently, until glaze has thickened slightly.
Poke warm cake with fork every inch. Pour glaze slowly over cake. Cool completely, about 1 hour.
In a 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 at room temperature.