LEMON FILLING:
3 egg yolks (reserve whites for meringue)
3/4 cup granulated white sugar
3 tbsp all-purpose flour
pinch of salt
3 tbsp lemon juice
2 tbsp lemon zest, loosely packed
1/2 cup water
2 tbsp unsalted butter, melted
CUPCAKES:
1/2 cup unsalted butter
1 cup sugar
2 eggs
3 tbsp lemon juice
2 tsp baking powder
1 tsp salt
1-1/2 cups all-purpose flour