In a 3 to 4-quart saucepan over medium
heat, stir marshmallows with half-and-half until melted, about
5 minutes.
Nest pan in ice water; stir often until
cool, about 3 minutes. Add lime peel, lime juice and tequila;
stir occasionally until cold, 8 to 10 minutes.
Meanwhile, in a food processor, whirl
cookies until finely ground. Add butter and whirl until mixed.
Press cookie mixture evenly over bottom and halfway up sides
of a 9-inch round cake pan with removable rim.
In a bowl with an electric mixer on high
speed, whip cream with sugar until it holds soft peaks. Fold
in marshmallow mixture, blending well.
Pour filling into crust and spread level.
Freeze until firm to touch in the center, about 1 hour, then
wrap airtight and freeze until solid, at least 2 hours longer
or up to two weeks.
Unwrap pie, run a thin knife between crust
and pan rim, and remove rim. Set dessert on a flat plate. Let
stand at room temperature about 10 minutes to soften slightly,
then cut into wedges. Garnish with a twist of lime, if desired.
