Pulse gingersnaps in food processor until fine crumbs (about 1 3/4 cups). Reserve 1/2 cup. Add butter to the remaining crumbs and pulse to mix. Press mixture in the bottom of a 10-inch spring form pan. Freeze for 1/2 hour.
Fold crystallized ginger into softened vanilla ice cream. Spread half of this mixture over the crust and top with 1/2 jar of Lemon Curd and sprinkle with reserved 1/2 cup gingersnap crumbs. Spread remaining ice cream mixture over crumbs and freeze 1/2 hour or more. Top with remaining Lemon Curd. Freeze at least 4 hours.
Using a 5 hole lemon zester, remove yellow peel from lemons in long strips.
Squeeze 2/3 cup lemon juice into a small bowl and strain.
Combine lemon juice and 1 cup of sugar in a small saucepan and bring to a simmer, stirring until sugar dissolves. Continue to simmer until slightly syrupy. Add lemon peel and cook until soft. Strain syrup and remove peel.
Toss peel in 2 Tablespoons sugar and transfer to a small sheet pan, separating with a fork. Allow it to dry 2-4 hours.
Garnish frozen torte with candied lemon peel and serve.