1 box Pillsbury White Cake mix (plus ingredients for the cake)
1 can (14 oz) sweetened condensed milk
1/2 cup, plus another 3/4 cup half n half or heavy cream
1/2 cup lime juice
optional: green food coloring
1 container (12 oz) whipped vanilla frosting or 2-3 cups lightly sweetened whipped cream (you can add a bit of lime juice for a bit more flavor)
optional: limes for garnish
Prepare cake mix according to package directions
Poke holes in cake with handle of spoon. (Poke lots of holes- the more there are, the better the cake will turn out.)
Evenly distribute 1/2 cup half n half/cream into the holes on the cake
In large bowl, mix sweetened condensed milk and 3/4 cup half n half/cream together
Working very quickly, add lime juice to mixture and pour over cake. (Once you have added the lime to the milk mixture, the filling sets very very fast.) Work the lime filling into all the holes with a spatula. There will be a good amount of filling left on top of the cake.
Put cake into fridge for at least and hour.
Gently spread frosting/whipped cream over the top of cake.