Bring the butter and cream cheese to room temperature. It will be difficult to work with these ingredients cold.

Preheat the oven to 375 degrees F. Line two 11 x 17 inch baking pans with waxed paper. Grease and flour the pans well. This step is VERY important. The cake will stick to the pans if you skip any part of this step.

Combine the flour, salt, baking powder, banking soda, and pumpkin pie spice in a small bowl.

In a medium bowl, mix the eggs, and granulated sugar until well combined. Mix in the pumpkin.

On the lowest setting, add the flour mixture in thirds to the pumpkin mixture.

Pour the mixture evenly between the two pans. If desired, sprinkle one of the pans with the chopped walnuts. I always make one roll without nuts just in case someone is allergic.

Bake for 11-14 minutes. While the cake is baking, sprinkle two clean towels with powdered sugar. Tip: don't use fabric softener on these towels. The strong scent of the softener can transfer to your cake. Start checking for doneness at 11 minutes. The cake is done when a toothpick comes out clean and the cake bounces back when pressed.

Immediately after baking, flip the pans onto the towels. The cakes should easily release from the pans with the waxed paper attached. Carefully peel off the waxed paper.

Starting with the narrow end, roll the towel and cake together as if they were one. Let it sit until cool. I didn't have a wire rack, so I cooled these on an upside down muffin tin.

Mix the cream cheese, butter, and vanilla on a low setting until smooth. To prevent any lumps, it's a good idea to sift the sugar if you have the time, but I've had success without sifting. Slowly add the powdered sugar to the butter mixture.

After the cake is cool, spread the filling evenly onto each cake, stopping at approximately 1/4 to 1/2 inch from the narrow edges. Frosting the cake all the way to the edge can result in overflow and a mess when you re-roll the cake.

Re-roll the cake and wrap with plastic. Refrigerate for at least an hour before slicing. Slice to desired thickness (I slice mine about 1 inch thick) and sprinkle again with powdered sugar if desired.