Preheat oven to 350*F. Grease a Bundt or tube pan.
In a food processor, grind the carrots for 1 to 2 minutes, almost to a puree. Remove them to a small bowl and set aside.
Grind the streusel ingredients in the food processor for 1 minute.
In a large bowl, combine flour, cinnamon, nutmeg, cardamom(if using), baking powder and soda, and salt. In a smaller bowl, whisk together the eggs, sugar, oil, ground carrots, poppy seeds, and sour cream. Add the liquid mixture to the dry, stirring with a wooden spoon. Transfer half the batter to the cake pan. Sprinkle half of the streusel onto the batter, then pour the remaining half of the batter over the streusel. Top with the remainiing streusel.
Bake the cake for 1 hour or until a knife inserted into the center comes out clean. Let the cake cool in its pan for 30 minutes. Invert it onto a serving dish. Serve the coffeecake at room temperature. Enjoy!