To make cookie dough, sift flour onto a pastry board or into a large bowl.
Add egg, unflavored sugar, vanilla sugar and butter; knead to a dough.
Press into a ball and wrap in foil or plastic wrap.
Refrigerate 2 hours.
Preheat oven to 400°F (205°C).
Grease a baking sheet.
Cut small pieces from cookie dough; form into sausage shapes about 1/2 inch (1 cm) thick.
Make a letter from each sausage and flatten slightly.
Place on greased baking sheet.
Bake 8 to 10 minutes or until golden.
To make frosting, put powdered sugar into a small bowl.
Beat in enough lemon juice to give a spreading consistency.
Frost warm cookie letters.
Stick jelly bears onto frosting before it sets.