Preheat the oven to 375°F.
Combine flour, 1/2 cup pecans and butter in a medium bowl and mix well. Press onto the bottom of an 11 x 8-inch baking dish. Bake until lightly browned, about 15 minutes. Let stand to cool.
Place cream cheese in a medium bowl. Beat with an electric mixer set at medium speed until fluffy. Add confectioners' sugar and beat until mixture is light and fluffy.
Add 1 cup whipped topping to cream cheese mixture and fold in gently. Spread over cooled crust.
Whisk the eggs, lemon zest and sugar together in a large bowl. Whisk in the lemon juice. Place the bowl over a water bath and whisk constantly until it thickens. It will start to make ribbons.
In the meantime, soften the gelatin in water. Squeeze out excess water and when curd has thickened, add the gelatin to the bowl.
Using a submersion blender, start mixing the curd and add the small pieces of butter. The curd will start to change in color and become lighter. Add all the butter and continue to mix till well combined.
Spread on top of cream cheese layer. Top with the remaining whipped topping. Sprinkle with remaining pecans. Chill, covered, for 1 hour. Store any leftovers in the refrigerator.