Step 1

Heat oven to 350ºF.

Step 2

Reserve 2 Tbsp. drink mix; place remaining drink mix in large bowl. Add 1/2 cup water; stir until mix is dissolved. Add cake mix, sour cream, eggs, oil and half the lemon zest; beat with mixer until blended. Pour into 13x9-inch pan sprayed with cooking spray.

Step 3

Bake 40 to 43 min. or until toothpick inserted in center comes out clean. Cool cake completely. Meanwhile, toss remaining zest with 1 Tbsp. of the reserved drink mix; freeze.

Step 4

Add remaining water to remaining drink mix in medium bowl; stir with whisk until mix is dissolved. Gradually stir in sugar until blended; drizzle over cake. Garnish with frozen zest.