Preheat the oven to 350°F, coat a 9" springform pan with nonstick spray, and line the bottom with parchment paper.
In a medium bowl, whisk together the flour, baking soda, salt, cinnamon, ginger, nutmeg, and clove. Set aside.
In a large bowl, using a hand or stand mixer with the paddle attachment, cream together the butter, C&H® Dark Brown Sugar, and C&H® Granulated Sugar until light and fluffy.
Mix in the egg yolk, pumpkin puree, and vanilla extract.
Once smooth, mix in half of the dry ingredients. Once it's almost combined, mix in the rest. Stop when the dry ingredients are mostly mixed in with a few streaks of flour throughout.
Pour in 1 cup of chocolate chips and fold to distribute the chocolate chips and finish mixing that last bit of flour.
Spread into your prepared pan and sprinkle the extra 1/4 cup of chocolate chips on top. Lightly press them into the surface.
Bake for 32-37 minutes, or until the center of the cookie cake has a tight jiggle when the pan is nudged.
Allow the cookie cake to cool in the pan for about 20 minutes. Then remove the ring and place the cookie in the refrigerator for about 45 minutes to cool completely. If it's too warm, the buttercream on top will melt so it's important that it's at least room temperature before moving on to the next step.
Using a hand or stand mixer with the whisk attachment, whisk the butter until smooth.
Mix in 1 cup of C&H® Powdered Sugar, followed by the vanilla extract. Then, once smooth, mix in the remaining half cup of C&H® Powdered Sugar.
If it's too thick, mix in 1 tablespoon of milk or water to help thin it out.
Add 2 small pinches of cocoa powder to the buttercream and mix to combine. It shouldn't color it at all, but this will give it a slightly warmer tone.
Add one spoonful of the frosting to a small dish and 4 spoonfuls to another dish. Now you should have 3 bowls of buttercream (one small, one medium, and one large).
To the small dish, add 1 tsp of cocoa powder and mix to combine. This will act as the stems of the pumpkins.
To the medium dish, add a drop of orange gel food coloring and 1/4 tsp of cocoa powder. The cocoa powder helps mellow out the orange, so it looks more natural, like the color of actual pumpkins.
The large dish (the original buttercream mixture) is to remain white. Add the white buttercream to a piping bag fitted with a large French star tip. Add the orange to a bag fitted with a small French star tip. And finally, add the chocolate buttercream to a bag fitted with a small round tip.
When the cookie cake is completely cooled, start by piping on the white buttercream in small dollops all around the rim of the cake. Fill in any gaps with the orange buttercream, and then add your chocolate stems on top of each pumpkin.
Now slice and enjoy!
When preparing your pan, spray the pan, remove the ring, place a sheet of parchment paper on the bottom pan, and place the ring on top to seal it in place. No need to cut a perfect circle.