Preheat oven to 450°.
Combine egg whites (at room temperature), cream of tartar, and salt in a large mixing bowl; beat until frothy. Add sugar, 1 tablespoon at a time, beating until stiff peaks form and sugar dissolves. Add vanilla and cardamom; beat at medium speed of an electric mixer 5 minutes.
Spoon meringue mixture into 10 equal portions on baking sheets covered with unglazed brown paper. (Do not use recycled paper.) Using back of spoon, shape meringue into circles 4 inches in diameter; shape each circle into a shell. (Sides of shells should be about 1 1/2 inches high.)
Place baking sheets on lower rack in preheated oven; immediately turn oven off. Allow meringue to cook and cool in oven overnight. (Do not open oven door.) Carefully remove baked meringue shells from brown paper. Use immediately or store in airtight containers.
Fill meringue shells with ice cream, and place on individual dessert plates. Serve immediately.
Note: If desired, prepare 8 meringue shells, and pipe remaining egg white mixture into small bows. Bake shells and bows as directed. Fill meringue shells with ice cream, and garnish with bows.