Beat butter at medium speed with an electric mixer until creamy. Add 3/4 cup sugar, beating until smooth. Add molasses, cinnamon, and cardamom, beating until blended.
Combine 1 tablespoon water and baking powder, stirring until baking powder is dissolved; add to butter mixture. Gradually add flour to butter mixture, beating until blended. Cover; chill 8 hours.
Turn dough out onto a lightly floured surface; roll to 1/4-inch thickness. Cut with a 2-inch round or other desired shape cutter. Place, 2 inches apart, on lightly greased baking sheets. Brush evenly with egg white, and sprinkle with sugar.
Bake at 375° for 8 minutes or until lightly browned. Cool on baking sheets 5 to 6 minutes. Remove to wire racks to cool completely.