Preheat oven to 350°F. Line a baking sheet with parchment paper. Set aside.
In a medium-sized bowl, whisk together flour, cocoa powder, baking soda, baking powder, salt, and espresso powder. Set aside.
In a large bowl, add the butter, brown sugar, and sugar. Using a stand mixer or hand mixer, beat until light and creamy, about 3 minutes.
Add egg yolks, and vanilla extract. Beat until well combined. Scraping down sides of bowl as needed.
Add dry ingredients and mix on low speed until combined. Scrape down sides of bowl.
Using a cookie scoop, scoop about 2-3 tablespoons of dough onto prepared baking sheet, about 3 inches apart. Bake for 12-15 minutes, until cookies spread out and the top begins to crack (be careful not to overbake the cookies, they should be soft when removed from oven). Transfer to a wire rack to cool completely.
Chocolate Ganache
Heat up heavy cream in a microwave or on the stove until steaming and very hot, but not boiling.
Add chocolate chips to a small bowl. Pour hot cream over chocolate and let sit for 5 minutes. Stir until the mixture becomes smooth and glossy.
Green Icing
In a small bowl, stir together powdered sugar,1 tablespoon heavy cream, and green food coloring. Add more heavy cream if needed to reach the correct consistency. Add to a piping bag, cut a small whole into the tip of the bag.
Decorate
To assemble the cookies, smooth the ganache over the top of each cookie. Pipe the green icing on top to look like vines. Add a candy pumpkin to each. Enjoy!