Juice the limes and strain to remove pulp and seeds. You need about 3/4 cup of fresh lime juice for the authentic flavor.
In a blender, combine cold evaporated milk, condensed milk, lime juice, and vanilla extract. Blend on medium speed for 30 seconds until smooth and slightly thickened.
Line an 8x8 inch square baking dish or 9 inch springform pan with parchment paper, leaving overhang on the sides for easy removal.
Pour a thin layer of lime cream mixture onto the bottom of the prepared pan, just enough to coat the surface evenly.
Arrange a single layer of Maria cookies over the cream, breaking cookies as needed to fill gaps. Fit about 9 cookies per layer depending on pan size.
Pour approximately one quarter of the remaining lime cream over the cookies and spread evenly with a spatula to create the first layer.
Repeat the layering process three more times, alternating cookies and cream, always ending with a layer of lime cream on top.
Cover tightly with plastic wrap and refrigerate for at least 4 hours, though overnight chilling produces the best texture and flavor.
When ready to serve, beat cold heavy cream with sugar using an electric mixer until medium peaks form.
Spread the whipped cream over the top of the chilled Carlota. Garnish with lime zest, crushed Maria cookies, and lime slices if desired.
Slice with a sharp knife dipped in warm water for clean cuts. Serve immediately while cold for the best texture.
