Grease and sprinkle with flour a 9-x-13 inch cake pan.
Prepare white cake mix according to box instructions. Pour batter into the prepared pan and bake for about 25-30 minutes, or until a toothpick inserted in the center comes out clean. Let cool for 10 minutes and using the bottom of a wooden spoon, poke holes all over the cake.
While the cake is cooling, mix gelatin with boiling water until gelatin is fully dissolved and pour the mixture all over the cake.
Spread the lime curd evenly on top of the cake, making sure to get the filling inside the holes and at the corners of the cake.
Let cool to room temperature.
Lime Whipped Cream:
In a large bowl, beat all the ingredients until stiff peaks form.
Using a spoon, scoop the lime whipped cream all over the cake and spread it with a spatula in an even layer. Smooth the top and refrigerate the cake overnight or for at least 8 hours before serving.
Before serving, garnish with fresh lime zest and lime slices.