Pace butter, sugar & juice in a medium saucepan. Whisk over low heat until the butter is melted & sugar is dissolved; remove from heat. Vigorously whisk in eggs. Whisk constantly over low heat for 8 to 10 minutes or until thickened; strain through a fine sieve. Pour into sterilized jar; seal with sterilized lids. Chill for 8 hours or overnight until cold. Cover & chill until completely cooled.

Preheat oven to 325°F (160°C). Grease and line a 9 x 13-inch (23 x 33cm) baking pan with parchment (baking) paper. In a food processor, process cookies & butter until fine crumbs. Press over base of pan (a flat bottom glass works good for this); chill until ready to use.

In a food processor, process all ingredients until completely smooth; spread over crumb base. Dollop lemon curd over filling & carefully swirl through the filling using a flat-bladed knife or skewer & being careful not to touch the base. Bake for 40 to 45 minutes or until set. Let cool before covering & chilling in the fridge for 8 hours or overnight. Cuts into 18 - 24 pieces.