Preheat oven to 350 degree F. Place dough in a large mixing bowl; knead in as much flour as necessary and the cardamom until dough is easy to handle. Roll out dough on a well-floured surface to 1/8-inch thickness. Cut out cookies using 3-inch, 2 1/2-inch, and 1 3/4-inch scalloped-edged cookie cutters.
Bake on ungreased cookie sheets for 7 to 9 minutes or until edges are firm and bottom of cookies are lightly browned. Cool on cookie sheet for 1 minute. Transfer to a wire rack and cool completely.
Spoon the Royal Icing over cookies, leaving some cookies without any icing. Let stand until thoroughly dry (2 hours or overnight). To apply the luster dust, use a small soft brush to lightly brush some of the iced cookies and all of the uniced cookies with the powder. To decorate cookies with additional Royal Icing, snip a small piece from one of the corners of the plastic bag. Pipe icing over cookies. Let dry thoroughly.
In a large mixing bowl combine meringue powder, warm water, powdered sugar, and cream of tartar. Beat with an electric mixer on low speed until combined. Continue beating on high speed for 7 to 10 minutes or until mixture is stiff. Remove 1/4 cup of the icing; place icing in a small resealable plastic bag. Seal bag and set aside until glazed cookies have dried. Add water to remaining icing, 1 teaspoon at a time, to create an icing that is the consistency of thick paint.