1. Zest all six lemons, then juice them until you have one cup of lemon juice.
2. In a medium pot, combine juice with sugar, salt, and eggs; mix very well. Cook on medium heat, whisking or stirring well with a fork until the outside edges bubble, about 15 minutes. Cool.
3. Mix ice cream with lemon zest, about three-quarters of the lemon curd, and cookies until the elements are lightly layered and mixed together but not completely combined.
4. Freeze completely. Serve with remaining lemon curd spooned over the top.