Step 1: Preheat oven to 350°F (175°C). Line a 15x10-inch jelly roll pan with parchment paper, extending it slightly over the edges.
Step 2: In a medium bowl, whisk together the flour, baking powder, baking soda, cinnamon, ground ginger, nutmeg, and salt. Set aside.
Step 3: In a large bowl, beat the eggs and 1 cup sugar with an electric mixer until light and fluffy. Stir in the canned pumpkin and grated carrots until well combined.
Step 4: Gradually add the dry ingredient mixture to the wet ingredients, mixing on low speed until just combined. Do not overmix. If using, fold in the chopped walnuts.
Step 5: Spread the batter evenly into the prepared baking pan. Bake for 13–15 minutes, or until the cake springs back when lightly touched.
Step 6: While the cake is still hot, immediately invert it onto a clean kitchen towel heavily dusted with confectioners’ sugar. Carefully peel off the parchment paper.
Step 7: Starting from a short side, carefully roll the cake and the towel together. Place the rolled cake seam-side down on a wire rack and let it cool completely.
Step 8: Prepare the Cream Cheese Frosting: In a medium bowl, beat the softened cream cheese and unsalted butter with an electric mixer until smooth and creamy.
Step 9: Gradually add 1 cup confectioners’ sugar and vanilla extract, beating until light and fluffy.
Step 10: Once the cake roll is completely cool, carefully unroll it. Spread the cream cheese frosting evenly over the entire surface of the cake.
Step 11: Gently re-roll the cake without the towel. Wrap the finished cake roll tightly in plastic wrap and chill in the refrigerator for at least 1 hour before serving.
Step 12: Before serving, dust the chilled cake roll with additional confectioners’ sugar. Slice into cubes or thick slices and serve.