Preheat your oven to 350°F (180°C).
Grease a 9x13 inch baking pan with non-stick cooking spray.
In a large mixing bowl, combine the cake mix, water, vegetable oil, eggs, and lime juice. Beat with an electric mixer until well combined.
Pour the batter into the prepared pan and bake for 25-30 minutes, or until a toothpick inserted into the center of the cake comes out clean.
While the cake is baking, make the lime curd. In a medium-sized saucepan, whisk together the eggs, the lemon juice, lemon zest and sugar until well combined/ Place the saucepan over medium heat. Cook the mixture, whisking constantly, until the mixture is smooth. Continue to cook the mixture over medium heat, whisking constantly, until it thickens and coats the back of a spoon, about 8-10 minutes.
Remove the saucepan from the heat and add the butter in cubes and mix until it dissolves and the texture is creamy.
Transfer the lemon curd to a clean container and let it cool to room temperature.
Once the cake is done, use the handle of a wooden spoon to poke holes all over the cake, making sure to go all the way to the bottom.
Pour the lime curd over the cake, making sure it gets into all the holes.
Refrigerate the cake for at least 1 hour or until the curd has set.
In a medium bowl, use an electric mixer to whip together the heavy cream, powdered sugar, and vanilla extract until stiff peaks form.
Spread the whipped cream topping evenly over the cake.
Cover the cake and refrigerate for at least another hour before serving.
Decorate with lime slices and serve.