Preheat oven to 350° F. Line a jelly roll pan (10 inches by 15 inches) with parchment paper so that the parchment is flat on the bottom and comes up at least one inch on the 10 inch sides of the pan. (This extra parchment on the short sides of the pan will make it easy to lift to hot cake from the pan when it comes out of the oven.) Spray the pan with non-stick cooking spray, making sure to coat the sides along the 15 inch sides. Place parchment back into the pan and spray it will a little more non-stick cooking spray.
In a small bowl, whisk together the flour, graham cracker crumbs, baking powder, salt, cinnamon, ginger, nutmeg, and cloves. Set aside, but hold onto the whisk.
In the bowl of an electric mixer with the whisk attachment, whisk the egg whites on low-medium speed until they start to get foamy. Increase the speed to medium-high. Once the mixture is mostly white and not clear, slowly add only half (approximately 75 g.) of the sugar with the mixer running. Add just a little bit, let it get incorporated into the whites, then add a little more. Keep repeating until you have used apprxomately half the sugar. Set the remaining sugar aside. Increase the mixer speed to high and whisk until the egg whites are shiny and stiff.
While the egg whites are beating, in a separate, large mixing bowl, whisk (use the one you used on the dry ingredients) together the egg yolks and the rest of the sugar until thick and pale in color. Whisk in the sour cream, vanilla and molasses.
Fold some (no more than ⅓) of the stiff egg whites into the egg yolk/sugar/sour cream mixture just until the are barely any white streaks. Add another ⅓ of the whites and fold until almost incorporated. Add the remianing egg white and fold just until fully incorporated.
Fold in half the dry ingredients until almost fully combined. Fold in the remaining dry ingrdients just until fully incorporated.
Fold in the carrots to the batter.
Spread the batter into the prepared pan with a metal spatula, making sure it is even throughout the pan. Gently tap the pan on the counter to break any large air bubbles. Bake 14-18 minutes. A toothpick inserted should come out dry.
Within one minute of removing the cake from the oven, lift the cake from the pan by holding the parchment overlays along the 10 inch sides. Place the hot cake on a heatproof surface. Immedately and carefully roll the cake up. Allow the cake to cool completely while rolled up