Whisk together the evaporated milk and the lemon pudding mix and let it thicken slightly while you beat the cream cheese.
In the bowl of a stand mixer or with an electric hand held mixer, beat the softened cream cheese until light and fluffy. Gradually add the lemonade concentrate, beating until well mixed. Beat in the lemon zest and vanilla extract
Stir the lemon pudding mixture into the cream cheese mixture until smooth.
Divide the lemon mixture between the two unbaked crusts and cover with sheets of plastic wrap (or use the little plastic dome that comes with the crusts). Freeze for at least 4 hours or until firm. Once firm, cover the pies with whipped cream or whipped topping. Garnish with Maraschino cherries if desired. Return to the freezer and keep frozen until about 30 before you are ready to serve.
To serve, allow the pies to stand at room temperature for about 30 minutes before slicing. Alternatively, you can pop the pies out of the crust and cut into slices while frozen. Plate, then let the plated pie slices come to room temperature. If you are only serving 2 or 3 people, you can plate the frozen pie slices and put the rest in a freezer bag for later.