Preheat the oven to 350°F. Line three 6-inch cake pans with parchment paper.

To make the batter: In a large mixing bowl, add the canola oil, heavy whipping cream, cane sugar, eggs, and vanilla extract. Whisk together until combined.

Add the flour, black cocoa powder, baking powder, and fine sea salt.

Mix on low until combined into a smooth batter.

Transfer the batter to the prepared baking pans, they should weigh about 400 grams each.

Bake for 35 to 37 minutes or until a toothpick inserted in the center comes out clean. Allow to cool completely in the cake pans.

To make the frosting: In the bowl of a stand mixer fitted with the paddle attachment, add the butter, powdered sugar, black cocoa powder, heavy whipping cream, and vanilla extract. Mix on low until combined and then speed mixer up to high and mix for at least 1 minute or until light and fluffy. Fit a piping bag with Ateco tip #827 and add most of the black frosting into the bag. Transfer the remaining frosting to an additional piping bag with a coupler. Add in Ateco tip #30 to the piping bag.

Once the cake is fully assembled, pipe a few large rosettes on top of the cake with Ateco tip #827.

Fill in the gaps with small roses using the piping bag with Ateco tip #30. Then switch to Ateco tip #68 and pipe leaves anywhere you like.

Place some of the marshmallow crème into a piping bag and cut a small hole. Pipe small drizzles of fluff onto the top and sides of the cake to resemble spider webs. Or you can also do this drizzling it on top with fork.