In large bowl, combine egg yolks, eggs, sugar and rum; beat 5 minutes or until thick and lemon colored. Add cream, blend well. With spoon, stir in flour and cardamom; mix well to form a soft dough. Wrap dough in plastic wrap; refrigerate 8 hours or overnight.
In deep fryer or heavy saucepan, heat 3 to 4 inches of oil to 365°F. On lightly floured surface, roll out 1/4 of dough at a time to 1/16-inch thickness. (Keep remaining dough refrigerated.) Cut dough into diamond shapes about 5x2 1/2 inches. Make lengthwise slit in center of each diamond; pull 1 pointed end through slit.
Drop dough pieces 3 or 4 at a time into hot oil. Fry 1 to 1 1/2 minutes or until puffed and deep golden brown. Drain on paper towels. Cool 15 minutes or until completely cooled. Repeat with remaining dough. Store in tightly covered container in cool dry place.
Just before serving, in small bowl, combine powdered sugar and cinnamon; mix well. Sprinkle lightly over cookies.