1. Coat an 8-or 9-in. springform pan with nonstick cooking spray.
2. Bring 2/3 cup water to a boil. Put gelatin and lime peel in a large bowl, add boiling water and dissolve gelatin as box directs. Pour lime juice into a glass measuring cup; add ice water to equal 2/3 cup. Stir into gelatin. Refrigerate, stirring occasionally, 20 minutes or until consistency of unbeaten egg whites.
3. Cut cake crosswise into 16 slices. Cut each slice in half diagonally to form 32 triangles. Fit half the triangles over bottom of prepared pan.
4. Mousse: Stir a large spoonful whipped topping into lime gelatin until blended. Remove 1 cup whipped topping and reserve. Fold remaining topping into gelatin mixture until blended.
5. To assemble cake: Spread 1/4 cup lemon curd over cake triangles in pan. Spoon on 1/2 the mousse, then spread in an even layer. Repeat layers once, starting with remaining cake. Spoon remaining lemon curd on top and gently spread to 1/2 in. from edges. Cover pan and refrigerate until mousse is firm, at least 4 hours.
6. Up to 2 hours before serving: Remove pan sides and transfer cake to a serving plate. Frost sides with some of the reserved whipped topping. Spoon remaining topping into a qt-size ziptop bag. Snip off tip of 1 corner and pipe dots of topping around top of cake.
Prep Time: 20 Minutes
chill: At least 4 1/2 hours
May be prepared through Step 5 up to 3 days ahead.
Date: June 15 2002