Preheat oven to 375ºF.
Grease and flour a 10x15 inch jelly roll pan with oil. Or, line pan with parchment paper and spray with avocado oil (that's the easy way!). Remember to be generous with your oil.
Mix together flour, baking powder, salt, and spices.
In the bowl of your stand mixer with the whisk attachment, beat eggs for 5 minutes (yes, the whole 5 minutes) until light and foamy.
Add sugar and stir until creamy, then gently fold in the pumpkin puree.
Fold in the dry ingredients and stir until just combined (don't overmix the batter, stir until there is no more visible flour).
Pour batter into prepared jelly roll pan and spread until even. Pick up the pan and tap it (the bottom of the pan) against the counter a few times to remove air bubbles. (I jumped when Grandma did this; it makes a bang!)
Bake for 13 to 15 minutes, until the cake is done.
While the cake is baking, place a clean flour sack or tea towel on the counter and sprinkle with a bit of powdered sugar.
As soon as the cake comes out of the oven, run a butter knife around the outside edge of the cake to separate it from the pan. Immediately, using hot pads, turn the pan upside down over the prepared towel. Pat the back of the pan, if needed, but the cake should fall out easily (especially if you used parchment paper).
As soon as the cake is out of the pan, place another clean flour sack towel on the short end of the cake and roll it up like a sleeping bag.
Cool the cake on a wire rack for about 30 minutes.