Colorful Heart Cookies
For the dough, on work surface, mix flour, butter, powdered sugar, egg yolks and vanilla sugar and knead quickly into a dough. Shape into a ball and wrap in plastic wrap. Refrigerate about 30 minutes.
On a floured surface, roll out dough about 3 mm (approximately 3/32 inch) thick and cut out heart shapes.
Place cookies on a greased baking sheet and bake at 200°C (approximately 400°F) about 10 minutes. Let cool.
Mix powdered sugar with a little water until thick icing forms. Divide icing and tint each to desired color with food coloring. Decorate cookies with icing and allow to dry.
To decorate, place paper strips with a congratulatory message between cookies. Place frosting on back of cookie and arrange paper strip in place. Stick cookies together with icing and arrange paper strip, so that message is visible.