1 box white cake mix, plus ingredients called for on box
FOR THE FILLING:
1 (14 oz) can sweetened condensed milk
3/4 cup heavy whipping cream
1/2 cup bottled key lime juice
Zest from 1 lime
FOR THE TOPPING:
1 1/2 cups heavy whipping cream
1 teaspoon vanilla extract
1/2 cup powdered sugar
Prepare and bake cake according to package instructions in a 9×13-inch baking pan.
Let cool for 5 minutes, then poke holes all over cake with the handle of a wooden spoon, but don’t poke through to the bottom. Set aside.
For the filling, add condensed milk, whipping cream and lime zest to a medium bowl. Whisk to combine. Add lime juice and once again, whisk to combine. It will start to thicken quickly; pour over cake, spreading with a spatula to encourage it to fill in holes. Chill for at least 1 hour, and up to overnight.
While cake chills, make the topping. To a medium bowl, add whipping cream and vanilla extract. Beat with an electric mixer until starting to thicken, then gradually add powdered sugar and continue beating until stiff peaks form.
Spread over cake and garnish with sliced limes and lime zest, if desired. Enjoy!