Preheat oven to 180C (350F). And line 8 holes of a muffin tray with papers.
Smash shortbread in a bag or whizz in the food processor until you have coarse crumbs. Divide crumbs between the muffin trays.
Combine egg yolks, condensed milk, lemon juice and zest in a bowl and place on top of the crumb bases.
Whisk egg whites until stiff. Gradually add sugar and continue to beat for a few more minutes until the sugar is dissolved.
Spoon whites on top of the lemon filling.
Bake for 10 minutes or until the meringue is golden. Cool before serving.
