For the cake, preheat oven to 325 F, and set a rack in the center. Line a 9” x 13” cake pan with parchment paper on the bottom and sides
Sift together the flour, baking powder, and spices into a medium bowl. In a separate mixing bowl, whisk together the sugar, pumpkin puree, oil, and egg yolks. Fold in the sifted flour mixture with a spatula until the flour is just hydrated. Do not overmix once you add the flour otherwise the cake might become tough.
In a clean bowl of a stand mixer place egg whites and whip on high speed with a whisk attachment. You can also use a handheld electric mixer for this. After 1-2 minutes, reduce speed to medium high until soft peaks form. This may take 4-5 minutes. When you lift the whisk from the egg whites, there should be a soft peak at the tip of the whisk.
Fold in one-third of the whipped egg whites into the wet flour mixture and mix with a spatula until well combined. Lightly fold in the rest of the meringue. Pour batter into the prepared pans. Bake in the preheated oven for 30-40 minutes, rotating the pan halfway. It is done when a cake tester is inserted in the center and comes out clean. Let the cake cool before filling it. You can bake the cake up to 2 days before assembling. Store the baked cake in an airtight container in the fridge.