01 - Preheat oven to 350°F. Lightly grease a 9x13-inch baking pan with cooking spray or butter.
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 the prepared pan and level the surface.
03 - Bake for 28-32 minutes until a toothpick inserted in the center comes out clean. Remove from oven and let cool for 10 minutes.
04 - Use the handle of a wooden spoon to poke holes evenly across the warm cake, spacing approximately 1 inch apart.
05 - Dissolve lime gelatin in boiling water, stirring until completely dissolved. Stir in cold water.
06 - Slowly pour the gelatin mixture evenly over the warm cake, allowing it to seep into the holes.
07 - Refrigerate cake for at least 1 hour until gelatin is completely set.
08 - Whisk together cold milk and vanilla pudding mix for 2 minutes until slightly thickened. Gently fold in whipped topping until fully incorporated.
09 - Spread pudding mixture evenly over the chilled cake. Garnish with fresh lime zest and green sprinkles if desired.
10 - Refrigerate for at least 30 minutes before serving. Cut into squares to serve.