In a large mixing bowl, whisk together all the dry ingredients.
In a high-powered blender, combine all the wet ingredients. Blend until the mixture is creamy.
Pour the blender mixture into the dry ingredients. Using a spatula, gently fold until well combined, achieving a fluffy and light batter.
Pour the batter into the prepared pan, smoothing the top. Bake in the preheated oven at 350F (180C) for 40 minutes, or until a toothpick inserted in the center comes out clean.
Whip on a medium speed with an electric mixer until the mixture is fully combined and has a smooth, creamy consistency. Refrigerate until the cake is completely cooled.
Remove the pan from the oven. Allow the cake to cool in the pan for about 10 minutes. Afterwards, transfer it to a cooling rack and let it cool completely. Spread the frosting on top of the cake and dust with cinnamon or pumpkin pie spice.
Store the cake in an airtight container in the refrigerator for up to 3 days.