1 tablespoon boiling water
1-1/2 cups powdered sugar
1/2 teaspoon vanilla
Few drops of lemon juice
1/2 teaspoon melted butter
Combine boiling water and sugar, stirring to make a paste stiff enough to spread; add vanilla, lemon juice, and melted butter. If too stiff, add a few more drops boiling water. Spread on warm pastry.