In your mixer combine and cream together the butter and powdered sugar until light and creamy.
Add in vanilla. Mix to blend.
Put flour, cornstarch, nuts and salt in a small bowl and whisk together.
Add flour mixture into butter and mix until blended.
Refrigerate dough for at least 1 hour.
Preheat oven to 325 F.
Grease cookie sheet or cover with parchment paper.
Drop cookie dough onto sheets in a rounded teaspoon, one inch apart
Use your thumb to press down into the middle of each ball making an indentation.
Bake for 15-18 minutes or until lightly browned around edges.
Fill indentation with lemon curd.