1In a blender, mix ricotta with the sweetened condensed milk and the lime juice.
2Assemble the trifle: cover the bottom of a 1 1/2 qt glass square dish with some cookies. If necessary, break cookie into pieces to cover any spaces in between. Pour some of the ricotta mixture just to cover. Sprinkle evenly with the mango pieces. Cover with more cookies and repeat layers, ending with a layer of the cheese mixture. Sprinkle with lime zest.
3Cover with plastic wrap, and refrigerate for at least 1 hour, preferably longer to meld the flavors.