01 - Preheat oven to 350°F. Grease a 9x13-inch baking pan thoroughly with cooking spray or butter.
02 - Combine white cake mix, water, vegetable oil, and eggs in a large bowl. Beat on medium speed for 2 minutes until smooth. Pour batter into the prepared pan and level the surface.
03 - Bake for 28 to 32 minutes or until a wooden toothpick inserted in the center comes out clean. Remove from oven and allow to cool for 10 minutes in the pan.
04 - Using the handle of a wooden spoon, poke holes evenly across the surface of the warm cake, spacing holes approximately 1 inch apart.
05 - Dissolve lime gelatin in 1 cup boiling water, stirring until completely dissolved. Stir in 1/2 cup cold water.
06 - Slowly pour the gelatin mixture evenly over the warm cake, ensuring the liquid fills the poked holes completely.
07 - Refrigerate the cake for at least 1 hour to allow the gelatin to set completely.
08 - Whisk together cold milk and vanilla pudding mix for 2 minutes until slightly thickened. Gently fold in the whipped topping until fully incorporated and smooth.
09 - Spread the pudding mixture evenly over the chilled cake surface. Sprinkle with fresh lime zest and green sprinkles as desired.
10 - Refrigerate the completed cake for at least 30 minutes before serving. Cut into squares and serve cold.