Preheat oven to 350ºF. Place six 4-inch tart pans with removable bottoms* on a baking sheet.
In a medium bowl, mix crushed cookies with melted butter until well combined.
Press crumb mixture firmly into tart pans with the back of a spoon or the bottom of a small cup. It’s important to press firmly, especially on the sides.
Bake tart shells for 8 minutes. Let cool completely.
In a medium bowl, stir mascarpone cheese with a spatula until smooth. Fold in lemon curd until well combined.
Fill cooled tart shells with mascarpone mixture. Refrigerate tarts until set, about 2 hours.
Carefully remove tarts from tart pans. Serve with a dollop of whipped cream if desired.