2 tablespoons water, lemon juice or dark rum, or a combination
Combine almond paste, sugar, egg and egg yolk in mixing bowl. Beat with paddle on medium speed until smooth. Add butter in 3 additions; beat until light. Lower mixer speed to low; beat in flour until absorbed.
WATER ICING: Combine sugar and liquid in a small saucepan and stir to a creamy consistency. Heat to luke-warm over low heat, stirring constantly. Apply warm; reheat if necessary.