With a citrus juicer, squeeze 4 or so limes until you have 1/2 cup of lime juice. Set aside.
In a blender, add one can of sweetened, condensed milk and one can of evaporated milk.
Blend until combined.
With blender on, slowly add lime juice. Blend until the cream reaches a pudding-like consistency.
Constructing the Cake
On a 7 inch aluminum brownie pan (or comparable) put down a layer of Maria cookies. (I fit 9 cookies on the bottom of my pan.)
Spread a generous layer of your cream mixture on the cookies.
Keep alternating layers of biscuits and cream, reserving about a half a cup of cream for the top.
Garnish with lime zest and a thin, twisted slice of lime.
Place in the refrigerator overnight (or at least 8 hours) to allow it to set up before serving.
Notes
To make the cake more sturdy, give the cookie layers a little mush when you lay them down.If you don't have a square pan, you can use a pie dish -- really any kind of baking dish will work.If the cookies don't fit perfectly, just break them in half to make them fit. The important things is to have a nice layer.If you wanted, you could also crush up your cookies for the bottom layer. Also there is no regulation height, so lay down as many or few layers as is feasible.