01 - Preheat oven to 350°F. Grease a 9x13-inch baking pan thoroughly.
02 - Combine cake mix, water, vegetable oil, and eggs in a large bowl. Beat on medium speed for 2 minutes until smooth. Pour batter into prepared pan and level the surface.
03 - Bake for 28 to 32 minutes until a toothpick inserted in center comes out clean. Remove from oven and let cool 10 minutes.
04 - Using wooden spoon handle, poke holes evenly across warm cake, spacing approximately 1 inch apart.
05 - Dissolve lime gelatin in boiling water, stirring completely. Mix in cold water.
06 - Pour gelatin mixture slowly and evenly over cake, allowing it to absorb into holes.
07 - Refrigerate for at least 1 hour until gelatin sets completely.
08 - Whisk cold milk and vanilla pudding mix for 2 minutes until thickened. Fold in whipped topping until smooth and uniform.
09 - Spread pudding mixture evenly over chilled cake. Sprinkle with lime zest and green sprinkles if desired.
10 - Refrigerate at least 30 minutes before serving. Cut into squares to serve.