For the pie crust, finely ground digestive cookie into crumbs, add melted butter and mix well.

Firmly press the mixture into your mold, (mine is 4.5 inches, just enough for 2~3 people) put into the freezer for 30 minutes.

For the lemon curd, put lemon juice, sugar and beaten egg in a sauce pan, mix together then add in butter, put on low heat just to melt the butter. (DO NOT BOIL)

After the butter has melted, add in cornstarch and turn off the heat immediately, whisk continually until thicken.

Wait until the mixture cool down, (do not put into the fridge or else skin will form on the top) add 2/3 of the zest, mix well.

Take out the pie crust, pour in the lemon curd mixture, sprinkle the rest of the zest on top, put into the fridge for two to three hours.

Enjoy!!