First preheat the oven to 350℉ & grease & parchment line a half sheet pan (12" x 18")
All ingredients are to be at room temperature before mixing the cake batter:Cream the vegan butter & sugar on medium high speed until light & fluffy approximately 5 minutes. Add the plant milk slowly while continuing to mix on medium-low speed, scrape the bottom and sides of the bowl to ensure an even mix.
Sift the flour with the baking powder, salt, spices & the egg replacer (I do not reconstitute the egg replacer in liquids) Add to the creaming mixture while mixing on low speed just until incorporated. Add the pumpkin & mix well to combine.
Spread into the prepared pan & bake immediately in the preheated oven for approximately 25-30 minutes or when a toothpick inserted into the center comes out with moist crumbs.
While the cake is cooling, prepare the buttercream as per the recipe on that page & add the spices & the pumpkin at the last stage of mixing
Prepare the vegan ganache & set it aside to cool, but remains pour able.
Once the cake has cooled completely flip it out onto a cutting board, peel off the parchment paper & cut it in half down the center (like a book fold) so you now have 2 layers (If the cake has domed at all be sure to trim it as flat as possible)
Spread the pumpkin buttercream over one cake layer then place the other cake layer on top.
Pour ganache over the top (no need to cover the sides, as we are to cut the edges to expose the layers on each petit four as shown in the pictures)
Cut the rough edges (yes you are supposed to eat those!! Quality control!!)
Cut the sheet into perfect 1"x1" bite sized squares
Transfer to a serving platter and add a spot of ganache on each one